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SIMATIC

S7 - OPEN MODBUS / TCP Communication
via the integrated PN interface of the PLC
Manual

Preface, Table of Contents
Product Description

1

Getting Started

2

Commissioning

3

Parameterization

4

Licensing

5

FB MODBUSPN

6

Diagnosis

7

Sample Application

8

SIMATIC S7
S7 OPEN MODBUS / TCP
Communication via the
integrated PN interface of the PLC
Manual

Appendices
Literature
Glossary

Edition 2.4

Safety Precautions and
Warnings

This manual contains warnings, which you should note for your own safety as well as for
the prevention of damage to property. These warnings are indicated by means of a warning
triangle and are displayed as follows in accordance with the level of danger:
__________________________________________________________________
Danger
indicates that loss of life, severe personal injury or substantial damage
will result if proper precautions are not taken.

__________________________________________________________________
__________________________________________________________________
Warning
indicates that loss of life, severe personal injury or substantial damage can result if proper
precautions are not taken.

__________________________________________________________________
__________________________________________________________________
Caution
indicates that minor personal injury or property damage can result if proper precautions are
not taken.

__________________________________________________________________
__________________________________________________________________
Note
represents an important information especially significant to the product, handling of the
product or a specific part of this documentation.

__________________________________________________________________
Qualified
Personnel

The start-up and the operation of the device may only be carried out by qualified
personnel. Qualified personnel in the sense of the security advices of this manual are any
persons authorized to commission, ground and label devices, systems and electric circuits.

Use as prescribed

Please note:
_________________________________________________________________________
Warning
This device may only be used for applications as prescribed in the catalogue and the
technical description. Furthermore, they may only be used in conjunction with third-party
devices and components recommended and authorized by Siemens.
A successful and safe operation of this product is depends on proper transport, and correct
storage, installation and assembly as well as careful operation and maintenance.

®

®

SIMATIC and SIMATIC NET are registered trademarks of SIEMENS AG.
Trademarks

Since any other brand names in this manual may refer to trademarks, the use of these
names by third parties for their own purposes may infringe the rights of the owner.

Copyright © Siemens AG 2008 All Rights Reserved

Exclusion of Liability

Passing on and reproducing this document as well as using and
disclosing its contents is prohibited unless an explicit permission is
given. Offenders will be liable for damages. All rights reserved,
especially in the case of patent grant or registration of a utility model
or design.

We have checked the contents of this document with regard to its
conformity with the described hardware and software. Deviations,
however, cannot be excluded. Therefore, we cannot guarantee its
complete conformity. The information in this document is checked
regularly and necessary corrections are contained in subsequent
versions. We will be grateful for any suggestions for improvement.

Siemens AG
Industry Sector
Engineering and Construction
I IS IN E&C
P.O. Box 3240, D- 91050 Erlangen
IT4.Industry@siemens.com

Technical data subject to change.

Preface Preface Purpose of the Manual The information in this manual allows you to set up and put in operation the connection between a PLC with integrated PN interface and a device that supports the Open MODBUS/TCP protocol. The manual contains the following topics: • Production description • Getting Started • Commissioning • Parameterization • Licensing • Function block MODBUSPN • Diagnosis • Sample application Scope of this Manual This manual is valid for the following software: Product Identification number From version OPEN MODBUS/TCP 2XV9 450-1MB02 2.4 FB 102 “MODBUSPN” 3. Additional Sources of Information All additional information concerning PN PLCs and IM 151-8 PN/DP CPU (Startup.5 FB 105 “MOD_SERV“ 1.4 FB 103 “TCP_COMM” 3.4 1 . Manual edition 2.3 Note This manual contains the FB description valid at the time of publication.) can be found in the manuals SIEMENS SIMATIC S7-300 CPU 31xC and CPU 31x: Installation Operating Instructions A5E00105491-07 MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Contents of the Manual This manual describes the function of the Modbus function block and its parameterization.0 FB 104 “MOD_CLI“ 1. commissioning etc.

6ES7318-3EL00-0AB0 CPU319F-3 PN/DP. 6ES7315-2EH13-0AB0 CPU315F-2 PN/DP.Preface SIEMENS SIMATIC S7-300 CPU 31xC and CPU 31x. 6ES7317-2AJ10-0AB0 CPU317F-2 DP. Technical Specifications Manual A5E00105474-07 SIEMENS SIMATIC S7-400 Automation System S7-400 Hardware and Installation Operating Instructions A5E00850740-01 SIEMENS SIMATIC S7-400 S7-400 Automation System.. 6ES7315-2FH13-0AB0 CPU317-2 PN/DP.4 2 . SIEMENS SIMATIC Software System software for S7-300/400 System and standard functions Reference manual C79000-G7000-C503-02 MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. 6ES7317-2EK13-0AB0 CPU317F-2 PN/DP. 6ES7317-2FK13-0AB0 CPU317-2 DP. 6ES7317-6FF03-0AB0 CPU319-3 PN/DP. CPU Specifications Manual A5E00850746-06 SIEMENS SIMATIC Distributed I/Os ET 200S Interface Module IM151-8 PN/DP CPU Manual A5E02049033-01 SIEMENS Product Information on CPU315-2 PN/DP. Manual edition 2. 6ES7318-3FL00-0AB0 A5E01103134-03 Additional information concerning STEP7 can be found in the following manuals: SIEMENS SIMATIC Software Base software for S7 and M7 STEP7 user manual C79000-G7000-C502-.

Preface Additional Questions For further questions regarding the use of the FBs described in this manual.4 3 . Manual edition 2. 319. 414 and 416 as well as IM 151-8 PN/DP CPU. The descriptions apply to PN PLCs of series 315. Terminology This document uses the term PN PLC. please contact your Siemens partner who provided you with this function block. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. 317. Scope of Application The function block described in this manual establishes a connection between a PN PLC and third-party MODBUS devices.

.Table of contents Table of Contents 1 Product Description.................................................................................... 7-1 7................................................................................................................ 8-1 A Literature.................................................................................................................4 Diagnosis Messages of Called Blocks ...........................3 Example of Address Mapping................................................................................................................................................5 Diagnosis Messages of SFC24 ........2 Verification by the FB MODBUSPN.......4 Data and Standard Functions used by the FB ...................................................................................2 PLC – Assigning the IP Address .................................................................................................................................. 1-1 2 Getting Started ......1 Parameterization with the Wizard............................................2 Hardware and Software Prerequisites......................................................................................... 3-4 Parameterization of the Modbus Communication .................. 4-3 5 Licensing ................................................................................. 1 MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02................3 Diagnosis Messages of the FB MODBUSPN................ 6-1 6.............................................. 6-16 Diagnosis ............................................................1 Installing the Library on the STEP7 PG/-PC .......................... 2-1 3 Commissioning ................... 7-12 7........................ 3-2 3...................................................................................... 4-1 4..................... 6-15 6............ 7-2 7........2 Parameters of the Function Block MODBUSPN ................................................................ 6-12 6...................... 1-1 1............................... Manual edition 2....... 1-1 1.............3 Insertion of the Function Blocks into the Program. 4-2 4................................................................................................................ 6-1 7 6................................................. 7-3 7................................................................ 5-1 6 Function Block MODBUSPN ..............................5 Renaming Standard Functions .......1 Field of Applications.....................4 i .......... 7-12 8 Sample Application....................... 7-6 7........ 3-1 4 3............1 Functionality of the FB ..........................................................................................................................2 Editing the Parameterization ......................................................... 6-5 6............................... 3-1 3....................................................................1 Diagnosis via the Display Elements of the PLC .

Product description

1

Product Description

1.1

Field of Applications

Placement in the
System Environment

The function block described here is a software product for PLCs with
integrated PN interface of Simatic S7-300, S7-400 and IM 151-8 PN/DP CPU.

Function of the
FBs

With these function blocks, communication link is established between a
Simatic PLC with integrated PN interface and a device that supports the Open
MODBUS/TCP protocol.
Data transmission is carried out in accordance with the client-server principle.
The SIMATIC S7 can act as both, a client and a server, during the data
transmission.

Use of Port
Number 502

In general, the protocol uses the port 502. This port number has not been
released for all PN PLCs yet and is only possible when using a 319 CPU, an
IM 151-8 PN/DP CPU, a 414 CPU or a 416 CPU with the corresponding
firmware version. You can find the information about the released port
numbers on the internet:
http://support.automation.siemens.com/WW/view/en/34010717.
The PLC only allows a one-time use of a specific port number. Therefore
the PLC/FB cannot be addressed simultaneous from different devices on the
same port number.

1.2

Hardware and Software Prerequisites

Usable Modules

The function blocks have been tested on the PLCs with the product
identifications
CPU315-2 PN/DP
CPU317-2 PN/DP
CPU319-3 PN/DP
CPU414-3 PN/DP
CPU416-3 PN/DP
IM151-8 PN/DP

6ES7315-2EG10-0AB0
6ES7317-2EK13-0AB0
6ES7318-3EL00-0AB0
6ES7414-3EM05-0AB0
6ES7416-3FR05-0AB0
6ES7151-8AB00-0AB0

You can find the latest hardware prerequisites on the internet:
www.siemens.com/s7modbus.
Software Versions

The usage of the FB MODBUSPN is possible with STEP7 Version 5.4 SP4 or
higher.

MODBUS / TCP communication via the integrated PN interface of the CPU
2XV9450-1MB02; Manual edition 2.4

1-1

Product description

Memory
requirements

The FB MODBUSPN requires ca. 6 kbyte work memory and ca. 7 kbyte load
memory.
The FB MOD_CLI requires ca. 11 kbyte work memory and ca. 12 kbyte load
memory.
The FB MOD_SERV requires ca. 10 kbyte work memory and ca. 11 kbyte
load memory.
The FB TCP_COMM requires ca. 2 kbyte work memory and ca. 2 kbyte load
memory.

MODBUS / TCP communication via the integrated PN interface of the CPU
2XV9450-1MB02; Manual edition 2.4

1-2

Getting started

2

Getting Started

Procedure

1. Install “OpenModbusTCP PN CPU“ and insert the Modbus function blocks
into your SIMATIC project.
=> Section 3.1 to 3.3
2. Parameterize the connection parameters regarding your requirements
(IP-address, port number, etc.).
=> Section 4.1 and 4.2
3. Parameterize the Parameter-DBs MODBUS_PARAM regarding your
requirements (client/server, connect at start-up, register numbers,
DB numbers, etc.).
=> Section 4.1 and 4.2
4. Call the Modbus block FB102 in the required OBs.
=> Section 6.1
5. Parameterize the Modbus block for initialization and runtime.
=> Section 6.2
6. Load the user program into the PLC and license the Modbus block for this
CPU.
=> Section 5
.

MODBUS / TCP communication via the integrated PN interface of the CPU
2XV9450-1MB02; Manual edition 2.4

2-1

the sample projects and the manuals in English and German in the corresponding STEP7 directories.4 SP4. In the Windows Explorer. Requirements STEP7 has to be installed. Requirements Knowledge of AWL and basic knowledge of STEP7 and PLC is required. To initially access the Modbus library. use the browse function of the “Open” dialog for libraries. Installation Insert your Modbus CD into the CD ROM drive and follow step-by-step the instructions which are displayed automatically by the installation program. the sequences. Manual edition 2.Commissioning 3 Commissioning General Information The information below on STEP7 refers to Version 5. • the sample project in \Program Files\Siemens\Step7\Examples. 2. names and directories might be different. • the software registration form in \Program Files\Siemens\Step7\S7libs\Modbus_PN_CPU. In later versions. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.EXE to start the installation. navigate to the CD ROM drive. If the installation program does not start automatically. The manuals are also available as PDF files on CD.4 3-1 . 3. The manual can be accessed via short cut under \Program Files \Siemens\ Documentation as well. • the manual in \Program Files\Siemens\Step7\S7manual\S7Comm. Follow the step-by-step the instructions which are displayed by the installation program. please proceed as follows: 1.1 Installing the Library on the STEP7 PG/-PC What We Provide The attached CD contains a setup which installs the library “Modbus_PN_CPU”. Now you can find • the library in \Program Files\Siemens\Step7\S7libs. Double-click on the setup directory and then on Setup.

2 PLC – Assigning the IP Address Introduction Each node on the Ethernet network is identified by an internationally unique address. 2. 1. Ethernet.Commissioning 3. it is necessary to create a new S7 project with STEP7. you can assign an IP address in the Ethernet to this physical address. In this example. A double click on line X2 opens the object properties dialog of Ind.4 3-2 . a PLC 317-2 PN/DP is inserted. Following the steps below. This so-called MAC address is preset by the manufacturer and cannot be changed. Manual edition 2. Procedure Before the configuration. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Open HWConfig The PLC 317-2 PN/DP is inserted in slot 2 and the properties dialog box of the PN-IO interface X2 is mapped.

4 3-3 . Result: The properties window of Ethernet interface X2 for PLC 317-2 PN/DP closes. Click on "New" to assign a name for a new Industrial Ethernet subnet. Enter the IP address and the subnet mask. 5. To establish a connection via a router. Confirm your entries with "OK". Click on the "OK" button. Manual edition 2. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.Commissioning 3. Result: You created a new Industrial Ethernet subnet. 4. enter the address of the router as well.

1 or higher V2. Please note that the following versions of the FBs are a prerequisite for the faultless function of the FB MODBUSPN: TSEND TRCV TCON TDISCON V2. Manual edition 2.3 Insertion of the Function Blocks into the Program Content of the MODBUS library The following blocks are required for the Modbus communication: • MODBUSPN • MOD_CLI • MOD_SERV • TCP_COMM The blocks have to be copied from the library into your project. They can be inserted into your project for assistance purposes. Additionally. You can find this function in „Standard Library Æ IEC Function Blocks“. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.Commissioning 3.3 or higher V2. Blocks of the Standard Library The following blocks are required for the Modbus communication: • TSEND (FB63) • TRCV (FB64) • TCON (FB65) • TDISCON (FB66).2 or higher V2. You can find these blocks in Standard Library Æ Communication Blocks.1 or higher Furthermore the block FC10 EQ_STRNG is necessary. They have to be inserted into your project.4 3-4 . the library contains the parameter data block MODBUS_PARAM as a draft.

a network configuration in NetPro is not necessary. the Modbus parameters are defined. The parameter data block can contain parameter information of all defined connections.. The maximal number of coexistent connections depends on the PLC.. For each additional connection.. At first the connection parameters are defined. Connection Description DB MODBUS_PARAM The parameters to establish a connection and to execute the Modbus communication are defined as a structure in a parameter DB called MODBUS_PARAM.4 4-1 . subsequently. For each logical connection. This structure contains the connection parameters of both communication partners and the Modbus parameters. It is also possible to use a separate parameter data block for each connection.0 Connection 2: Connection parameters +714. a separate structure is required.0 Connection 2: Modbus parameters END_STRUCT . Structure of DB MODBUS_PARAM: Address Name STRUCT +0. STRUCT 650*i 650*i+64 Connection i+1: Connection parameters (65+i) Connection i+1: Modbus parameters END_STRUCT MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Several connections to different communication partners can be parameterized and established at the same time.0 +64.. Manual edition 2.0 Connection 1: Connection parameters Connection 1: Modbus parameters END_STRUCT STRUCT +650. The connections are established and terminated by means of the function blocks TCON (FB65) und TDISCON (FB66). the parameter data block must be expanded by or a new data block created with the structure for connection parameters and the Modbus parameters. .Parameterisation of the Modbus Communication 4 Parameterization of the Modbus Communication General Information For the communication via the integrated PN interface of the PLC. A prepared structure is part of the library “MODBUS_PN_CPU” and can be used as a sample.

e. Otherwise it becomes impossible to set up a connection. The complete structure (connection parameters and Modbus parameters) is created. how many register or bit areas are mapped to which DB or the differentiation between the S7 acting as server or as client. It is recommended to use the wizard for the parameterization of the block MODBUS_PARAM. Alternatives for Parameterization There are two alternatives for a parameterization of the connection and Modbus parameters.g. The first one is to use a Wizard. . e.1 Parameterization with the Wizard General Information With the wizard Modbus TCP Wizard you can easily parameterize the connection parameters as well as the Modbus parameters in the parameter data block MODBUS_PARAM. the used local interface and the IP address of the communication partner. Modbus Parameters The Modbus parameters define the mode of communication and the address reference.4 4-2 . 4. The structure of the connection parameter block is obligatory und may not be changed.automation.g. which offers an easy way to setup the connection parameters. Manual edition 2.Parameterisation of the Modbus Communication Connection Parameters The parameters of the connection are defined in the first block. You can find the wizard at http://support.2. The functions TCON and TDISCON can establish and terminate a connection by means of these parameters. The structure of the parameter DB has to remain unchanged to ensure proper communication.1 and 4. The second possibility is to edit the parameters in the structure in the data block with the editor of STEP7.2. The two opportunities are described in detail in the following sections 4.siemens. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.com/WW/view/en/31535566. A detailed structure can be found in section 4.

Structure of and Adaption of Connection Parameters For each logical connection one structure is required. If the number is already used. Manual edition 2.Parameterisation of the Modbus Communication 4.2 Editing the Parameterization Procedure Copy DB2 of the library Modbus_PN_CPU and insert them in your project. Fixed value: id W#16#40 A connection ID is assigned to each logical connection.4 4-3 . rename the DB. It is used for the internal calls of the T blocks (TCON. TRCV and TDISCON). Value range: W#16#1 to W#16#FFF MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. It is necessary to restart the PLC after the modification of MODBUS_PARAM. This ID must be unique within the complete parameter data block and has to be parameterized during the call of FB MODBUSPN. block_length This parameter describes the length of the connection parameters and must not be changed. The parameter of data block MODBUS_PARAM must not be changed during runtime. TSEND.

Active connection establishment: Passive connection establishment: next_staddr_len 2 0 This parameter defines the length of next_staddr as the distinction between the communication running via an external CP or via the integrated PN interface of the PLC. is defined here.automation. It is recommended that the Modbus client performs an active connection establishment while the Modbus server establishes passive connections. It is used by the function TCON when establishing the connection. If an unspecified connection is to be used. Active connection establishment: Passive connection establishment: local_device_id The local_device_id defines the IE interface of the used PN PLC. i. You can find further information on the internet: http://support. CPU 319. The value depends on the PLC. Unspecified connection: Specified connection: rem_tsap_id_len B#16#0 B#16#4 This parameter defines the length of rem_tsap_id. TCP (compatibility mode): TCP: B#16#01 with CPU315 and 317 <= FW V2. the IP address of the communication partner. IM 151-8 PN/DP CPU. rem_staddr_len The length of rem-staddr. The following values are necessary with the different PLC types. Manual edition 2. no IP address is required for the partner. Active connection establishment: Passive connection establishment: 0 2 rem_subnet_id_ len This parameter is currently not used. CPU 414 and CPU416 The values vary depending on the used firmware.Parameterisation of the Modbus Communication connection_type The structure of the connection is defined here.com/WW/view/en/24294554 active_est This parameter defines the way the connection is established (active or passive).4 4-4 . IM 151-8 PN/DP CPU CPU315 or 317 CPU319 CPU414 or CPU416 local_tsap_id_len TRUE FALSE B#16#1 B#16#2 B#16#3 B#16#5 The length of the parameter local_tsap_id (= local port number) is defined here.3 B#16#11 with CPU315 and 317 >= FW V2. the port number of the remote communication partner.e.siemens.4. PN interface of the PLC: B#16#0 MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Please assign the value B#16#0.

The value range depends on the PLC. With connection_type B#16#01 local_tsap_id[1] low byte of the remote port number in hexadecimal local_tsap_id[2] high byte of the remote port number in hexadecimal local_tsap_id[3-16] B#16#00 With connection_type B#16#11 local_tsap_id[1] high byte of the remote port number in hexadecimal local_tsap_id[2] low byte of the remote port number in hexadecimal local_tsap_id[3-16] B#16#00 next_staddr This parameter defines rack and slot of the corresponding CP. The representation depends on the parameter connection_type.1: With connection_type B#16#01 rem_staddr[1] = B#16#01 (1). When using the integrated PN interface of the PLC. rem_staddr[5-6]= B#16#00 (reserved) With connection_type B#16#11 rem_staddr[1] = B#16#C0 (192). Manual edition 2.Parameterisation of the Modbus Communication local_tsap_id This parameter defines the local port number.0. assign 0 to this parameter. With connection_type B#16#01 local_tsap_id[1] low byte of the local port number in hexadecimal local_tsap_id[2] high byte of the local port number in hexadecimal local_tsap_id[3-16] B#16#00 With connection_type B#16#11 local_tsap_id[1] high byte of the local port number in hexadecimal local_tsap_id[2] low byte of the local port number in hexadecimal local_tsap_id[3-16] B#16#00 rem_subnet_id This parameter is currently not used. The value range depends on the PLC.168.4 4-5 . MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. The representation depends on the parameter connection_type. rem_staddr[4] = B#16#01 (1). The port number has to be unique within the PLC. Please assign the value B#16#0. rem_staddr[2] = B#16#A8 (168). rem_staddr[3] = B#16#A8 (168). The representation depends on the parameter connection_type. rem_staddr[3] = B#16#00 (0). rem_staddr[2] = B#16#00 (0). rem_staddr In this array of bytes. Example: IP address 192. no IP address has to be entered. next_staddr[1-6] spare B#16#00 Reserved. the IP address of the remote communication partner is defined. rem_staddr[5-6]= B#16#00 (reserved) rem_tsap_id This parameter defines the remote port number. When an unspecified connection is used. assign 0 to this parameter. rem_staddr[4] = B#16#C0 (192).

MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. server_client TRUE: S7 is server FALSE: S7 is client single_write In operating mode “S7 is client” and single_write = TRUE write requests with length 1 are carried out with the function codes 5 and 6. With single_write = FALSE all write requests use the function codes 15 and 16.Parameterisation of the Modbus Communication Adaption of the Modbus Parameters The Modbus parameters in the block MODBUS_PARAM define the mode of operation of the Modbus communication and the address reference of Modbus addresses and SIMATIC addresses. Manual edition 2.4 4-6 .

65535 (W#16#0001 to W#16#FFFF) MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. 8 Data Areas 8 data areas are available to map the Modbus addresses in the S7 storage. db_x DB-Number 1 . The other 7 data areas are optional. these memory areas are read or written. the first request should be started after the connection was established (CONN_ESTABLISHED = TRUE) or an error has been reported respectively (ERROR =TRUE). only one DB can be accessed. This has to be taken into account during the parameterization. If data_type_x set to 0.4 4-7 . this data area is not used Identifier Data type Size 0 Area not used 1 Coils Bit 2 Inputs Bit 3 Holding Register Word 4 Input Register Word The parameter db_x defines the number of the data block in which the consecutively defined MODBUS registers or bits are mapped. Depending on the type of request. FALSE: establish connection when ENQ_ENR=TRUE TRUE: establish connection immediate after PLC start-up When connect_at_startup = TRUE. Manual edition 2. data_type_x db_x The parameter data_type_x defines the MODBUS data type which is to be mapped with this definition.Parameterisation of the Modbus Communication connect_at_ startup This parameter defines the point in time at which the connection is being established. Even if consecutive register numbers or coils are located in two different DBs. two requests are necessary to access them both. 0 cannot be used as DB number since it is reserved for system functions. It is possible to map more Modbus values (registers or coils) in one data block than could be processed with one telegram. At least the first data area has to be defined. With one request.

When accessing registers. the number of the data element of the S7 DB in which the last bit is mapped. Manual edition 2. start_x. the number of the data element of the S7 DB in which the last register is mapped. The parameter end_x must not be smaller than start_x. the initialization of the FB is stopped with an error. In case of an error occurring.Parameterisation of the Modbus Communication start_x end_x Start_x specifies the first register or bit address. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Accessing or changing the array is inadmissible. can be calculated with the following formula: DBW number = (end_x – start_x) ∗ 2 When accessing coils or inputs. End_x defines the of the last MODBUS address. which is stored in the data element 0 of the DB. can be calculated with the following formula: DBB number = (end_x – start_x +7) / 8 The defined memory areas must not overlap. Accessing or changing the array is inadmissible. internal_recv_ buffer This array is used internally for the received data within the FB. In section 6.3 you can find an example of the mapping of the MODBUS addresses to S7 memory areas. When start_x is equal to end_x.4 4-8 . one Modbus address (1 register or 1 bit) is allocated. end_x MODBUS address 0 to 65535 (W#16#0000 to W#16#FFFF) internal_send_ buffer This array is used internally for message data within the FB.

MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.4 5-1 . 2. The OB121 must be available in the CPU. Monitoring the block via the button is insufficient. „Data block“ -> „Open Online“ to open the DB. Parameterize the block in the cyclic OB (OB1 or cyclic interrupt OB) and in OB100 according to your requirements. Transfer the program to the PLC and turn it to RUN mode. Open the instance DB of the block MODBUSPN. Read the IDENT_CODE To read the IDENT_CODE please proceed as follows: 1. The licensing takes place in two steps: reading the IDENT_CODE and declaring the registration key REG_KEY. Manual edition 2.Licensing 5 Licensing General The block MODBUSPN must be licensed for each CPU individually.

Licensing 3. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Copy this string per copy/paste from the DB und and insert it in the form IT4Industry SOFTWARE REGISTRATION FORM..industry@siemens. Hereupon you will receive the registration key for your PLC. of the product package into the form.\Program Files\Siemens\Step7\S7LIBS\Modbus_PN_CPU during installation and is also available on the installation CD. Please send the form per e-mail to IT4Industry it4.com. Insert the License-No. 4.4 5-2 . The output IDENT_CODE shows an 18 character string. This form is stored in the library path . Manual edition 2.

REG_KEY” to the parameter REG_KEY of the block MODBUSPN. 4. Assign the value “DB3. The registration key can be set at run time. Copy the prepared license block DB3 of the library “Modbus_PN_CPU“ into your project. Choose in the menu “Edit > Initialize Data Block” – all values of the column “initial value” are copied to “actual values”. The block is now licensed for this CPU. Change over to the data view via the menu “View” -> “Data View”. 3. A STOP -> RUN transition is not necessary. Transfer the changed blocks to the PLC. 2. Manual edition 2. Declare the registration key in the data block as “initial value” to avoid a repeated insertion after reloading the PLC. Please proceed as follows to declare the registration key REG_KEY: 1. If the DB number is already used in your project. 5. rename the license DB.4 5-3 . The registration key REG_KEY should be stored in a global DB. Via this global DB all MODBUSPN blocks can receive the registration key (See also the following example). MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Open the data block in the SIMATIC manager with the editor in the declaration view. Open the license DB and copy the 17 digit registration key you received from IT4industry to the column “Initial value”.Licensing Declaration of the Registration Key REG_KEY The registration key REG_KEY must be declared for each call of the block MODBUSPN.

if the OB121 is not available. A cyclic error message regarding the missing license is displayed in the diagnostic buffer too. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.Licensing Missing or Wrong Licensing When the registration key is missing or a wrong one is detected. please check if the FC “EQ_STRING” is copied into the project. Manual edition 2. but the output STATUS_MODBUS is set to W#16#A090 “no valid license”. the SF LED (S7-300 and IM151-8) or the INTF LED (S7-400) of the CPU is flashing.4 5-4 . The error number of the missing license is W#16#A090. _____________________________________________________________ Modbus communication is carried out even with a missing or wrong registration key. _____________________________________________________________ Warning ! The CPU will turn to STOP mode. If this error code is shown although the registration key has been inserted.

It contains the main information on the FB. Manual edition 2.Function Block MODBUSPN 6 Function Block MODBUSPN 6. 2. The block MODBUSPN calls the blocks MOD_CLI (FB104) and MOD_SERV (FB105) internally.4 6-1 . The function codes 1. 5. the FB can be operated either in client or in server mode. the block MOD_SERV executes the function of Modbus server and the block TCP_COMM handles the connection management. the functionality multitasking in the sense of the MODBUS specification is not implemented. The block MOD_CLI comprises the function of Modbus client. The blocks provide the following functions: Online-Help • Connection and data handling by means of T blocks of the standard library • Generation of MODBUS-specific telegram header before sending • Verification of the MODBUS-specific telegram header when receiving • Verification whether the memory areas requested by the client exist • Generation of exception telegrams when errors occur (only when S7 is in server mode) • Data transfer to and from the parameterized DB • Time monitoring of the data reception as well as connection establishment and termination • Verification of the registration key The SIMATIC Manager provides an online help for the function block MODBUSPN. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. In the server operating mode. Mark the FB and press “F1” so that he online help is displayed. 3.1 Functionality of the FB General Information The function block MODBUSPN enables a communication between a PLC with integrated PN interface and a partner which supports Open MODBUS/TCP. 4. Depending on the parameterization. 6. 15 and 16 are supported.

• The runtime parameters are not evaluated during the start-up. Manual edition 2. A coexistent call of FB MODBUSPN in OB1 and a cyclic interrupt OB. MOD_SERV and TCP_COMM must not be called additionally in an organization block. • The initialization parameters are copied into the instance DB. If the block has not been licensed yet. the OB121 is called. OB35 is not permissible. ____________________________________________________________ Warning ! The CPU will turn to STOP mode. if the OB121 is not available. • While a request is being processed. • The values of the parameter data block MODBUS_PARAM are evaluated. e. the FB MODBUSPN is called in OB1 or in a cyclic interrupt OB. • In the cyclical operation mode. the functions of the function block are activated. • The initialization parameters must be set according to the station configuration.g. OB35) The subordinate blocks of the Modbus library MOD_CLI. e.4 6-2 . Start-up of the FB Cyclical Operation of the FB OB121 “Programming Error” The function block MODBUSPN is unconditionally called once in OB100.g. initialization parameters are ignored. The OB121 must be available in the CPU. _____________________________________________________________ MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. In case of cyclical operation. changes to the runtime parameters are ignored. • Corresponding to the runtime parameters.Function Block MODBUSPN Call of the FB For a correct program sequence the function block MODBUSPN has to be called in 2 organization blocks: • OB100 Start-Up and Cyclic OB (OB1 or cyclic interrupt OB. You will find more information regarding this matter in section 5 “Licensing“.

Multiple Communication Partners A PN PLC can establish multiple connections to various communication partners. the calls of the FB MODBUSPN in the OB100 and in the OB1 receive the same instance DB for one connection. Correspondingly. To ensure a proper operation and data transfer. active and passive. a strict division of the different connections to the corresponding communication partners is inevitable. A different instance DB is required for each additional connection. The termination of the connection is defined with the parameter DISCONNECT of FB MODBUSPN. It is recommended explicitly that the Modbus client executes the active establishment. there are the following requirements for each connection: • • • one connection parameter block and the related Modbus parameter in DB MODBUS_PARAM call of FB MODBUSPN in OB100 call of FB MODBUSPN in OB1 or cyclic interrupt OB In this case. During runtime the function TCON establishes the connection to the communication partner for both types of connections. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.Function Block MODBUSPN Connection Handling Active connection establishment can be carried out by the Modbus client as well as the Modbus server. Manual edition 2.4 6-3 . With a parameter of the connection parameter block (active_est). it is possible to define whether the PLC performs active or passive connection establishment. The point in time at which the connection is established is defined in DB MODBUS_PARAM (parameter connect_at_startup). The relevant information is read from the connection parameters of DB MODBUS_PARAM.

The output DONE_NDR is set. LENGTH. A new request can be initiated. When an error is recognized during verification. If the verification result is positive. LENGTH. the completed function is indicated at the outputs UNIT. TI and WRITE_READ. the response telegram is sent. Manual edition 2. START_ADDRESS. the FB is ready to receive a request telegram from the client. The request of the client is not answered. DATA_TYPE. the activated request is terminated with an error. When the monitoring time elapses (no response from the server). The completed transmission is reported to the user by setting the DONE_NDR bit. the request is terminated with an error. If the result is positive. Depending on the input parameters UNIT. TI and WRITE_READ. the necessary actions are taken and the request is terminated without error. a MODBUS request telegram is generated and sent to the partner station via the TCP/IP connection. At this point. a validity check is carried out. the ERROR bit is set and an error number is returned at the output STATUS. DATA_TYPE.4 6-4 . START_ADDRESS. The received telegram is verified. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Activation of the Function Block S7 is Server With the signal TRUE at the trigger input ENQ_ENR.Function Block MODBUSPN Initiate Request S7 is Client A rising edge at the trigger input ENQ_ENR initiates a request. An erroneous request telegram causes an error message and the ERROR bit is set. The client waits for the parameterized monitoring time RECV_TIME for a response from the server. The server remains passive and waits for a telegram from the client. After the receipt of the response telegram. The error number is returned in STATUS_MODBUS.

2 Parameters of the Function Block MODBUSPN Parameter Decl.4 6-5 . Manual edition 2. Type Description ID IN Connection ID.Function Block MODBUSPN 6. TSEND or TRCV) no Job processing TRUE No job processing active FALSE CONN_ ESTABLISHED OUT BOOL Connection established Connection terminated TRUE FALSE no DONE_NDR OUT BOOL S7 is Client: TRUE: Active request finished without errors TRUE FALSE no S7 is Server: TRUE: Request from the client was executed and answered MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. must be identical to the associated parameter in the local connection description WORD Value range Init 1 to 4095 yes W#16#1 to W#16#FFF DB_PARAM IN BLOCK_ Number of the parameter DB DB depending on PLC yes RECV_TIME IN TIME T#20ms to T#+24d20h31 m23s647ms no T#20ms to T#+24d20h31 m23s647ms no TRUE FALSE no TRUE FALSE no Character no Monitoring Time: wait for data from communication partner Shortest adjustable time: 20 ms. KEEP_ALIVE IN TIME Not used ENQ_ENR IN BOOL S7 is Client: Initiate request at positive edge S7 is Server: Ready to receive at TRUE signal DISCONNECT IN BOOL S7 is Client: TRUE: connection is terminated after reception of response S7 is Server: TRUE: connection is terminated when ENQ_ENR = FALSE REG_KEY IN LICENSED OUT BOOL BUSY STRING [17] OUT BOOL Registration key to activate the license License state of the function block: Block is licensed Block is not licensed no TRUE FALSE Operating state of the T functions (TCON. TDISCON. CONN_TIME IN TIME Monitoring Time: wait for establishing or termination of the connection Shortest adjustable time: 100 ms.

Function Block MODBUSPN Parameter Decl. TDISON) 0 to FFFF no STATUS_FUNC OUT STRING [8] Name of the function. OUTPUT if in SERVER mode) LENGTH IN/ WORD OUT Number of values to be processed (INPUT if in CLIENT mode. TRCV. Character no UNIT IN/ BYTE OUT Unit identification (INPUT if in CLIENT mode. OUTPUT if in SERVER mode) DATA_TYPE Coils Inputs Holding registers Input registers START_ ADDRESS IN/ WORD OUT MODBUS start address (INPUT if in CLIENT mode. Type Description Value range Init ERROR OUT BOOL An error has occurred TRUE no No error has occurred FALSE STATUS_ MODBUS OUT WORD Error number for protocol errors when evaluating a Modbus telegram 0 to FFFF no STATUS_ CONN OUT WORD Error number for connection errors during execution of the T blocks (TCON.4 no W#16#0000 to W#16#FFFF no W#16#0 to W#16#FFFF no 6-6 . OUTPUT if in SERVER mode) TI WRITE_ READ B#16#0 to B#16#FF no 1 2 3 4 0 to 65535 no Coils Reading function Writing function 1 to 2000 1 to 1968 Inputs Reading function 1 to 2000 Holding Register Reading function Writing function 1 to 125 1 to 123 Input Register Reading function 1 to 125 IN/ WORD OUT Transaction Identifier (INPUT if in CLIENT mode. Manual edition 2. OUTPUT if in SERVER mode) 0 to 255 no IN/ BYTE OUT Data type to be accessed: (INPUT if in CLIENT mode. which causes the error at STATUS_MODBUS or STATUS_CONN Character no IDENT_CODE OUT STRING [18] Identification for licensing Please order your license with this identification string. OUTPUT if in SERVER mode) TRUE FALSE MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. TSEND. OUTPUT if in SERVER mode) 0 to 65535 IN/ BOOL OUT Write access or Read access (INPUT if in CLIENT mode.

g. Range of Values For the range of values of the different parameters. They have to be copied to an additional memory area if you need to process them or to display the values in a VAT (STEP7 variable table).Function Block MODBUSPN General Information The parameters of the FB MODBUSPN can be divided into two groups: • Initialization parameters • Runtime parameters Initialization parameters are evaluated only during the call of OB100 and are adopted into the instance DB. the instance DB must be initialized again via a STOP Æ RUN transition of the PLC. PLC-specific restrictions must be taken into consideration. Runtime parameters can by modified during the cyclical operation.4 6-7 . After a modification of these parameters (e. they are only available for one PLC cycle. during the test phase). They are marked with “yes“ in the column “INIT“ in the table displayed above. the output parameters may only be evaluated when DONE_NDR is TRUE. In the operation mode S7 is server.e. i. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. The output parameters are displayed dynamically. A modification of the initialization parameters during run mode has no impact. it is not advisable to modify the input parameters while a request is active. Wait with the next request and the change of the parameters until the previous request ends with DONE_NDR or ERROR. Manual edition 2. In the mode S7 is client.

which are necessary for the communication between the PN PLC and the Modbus device. The parameter data block can contain a sequence of parameters for several connections. which is part of the parameter data block MODBUS_PARAM. an indication RECV_TIME < 20 ms causes an error message and the request is rejected.4 6-8 . DB_PARAM The parameter DB_PARAM assigns the number of the data block MODBUS_PARAM. During cyclic operation in the operating mode S7 is client. CONN_TIME The monitoring time CONN_TIME observes the connection establishment and the connection termination. TRCV has to be called twice. The connection ID unambiguously specifies the connection between the PLC and the communication partner. an error is reported. This is also true for the operating mode S7 is client with connect_at_startup = TRUE. In the operating mode S7 is server. The range of values for this parameter depends on the PLC. an indication RECV_TIME < 20 ms causes the use of the default time of 1. The shortest adjustable time is 20 ms. The monitoring time is started with the call of TRCV and stopped after the receipt of the telegram segment. If the monitoring time elapses. In the operating mode S7 is server. Manual edition 2. This parameter data block includes the connection parameters and the Modbus-specific parameters. RECV_TIME The monitoring time RECV_TIME observes the data input from the communication partner. the RECV_TIME is triggered. the corresponding error code is displayed at the output STATUS_CONN. In order to receive a Modbus telegram. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.Function Block MODBUSPN ID To each connection between the PN PLC and a communication partner a connection ID is assigned. With each call of TRCV. The shortest adjustable time is 100 ms. an indication CONN_TIME < 100 ms causes the use of the default time 5s. CONN_TIME < 100ms causes an error message and the request is rejected. This parameter is declared in plain text: “DBxy“. When CONN_TIME elapses. 0 cannot be used as a DB number since it is reserved for system functions. The connection ID defined in the connection parameter block has to be entered here and must be unique within the PLC. When the time RECV_TIME elapses. This connection ID is defined in the connection parameter block.2s. The ID can be set to values between 1and 4095. It is also possible to use different parameter data blocks for multiple connections. When operating various connections an individual ID is required for each logical connection. In the operating mode S7 is client. The interval between two requests is not taken into consideration. the active request is cancelled with an error. The RECV_TIME monitors the duration of the TCP stream.

none or a faulty license string was entered. If the output is FALSE.Function Block MODBUSPN ENQ_ENR Operating mode S7 is Client: The data transfer is initiated with a TRUE edge at the input. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Operating mode S7 is Server: The FB is activated with a TRUE signal at the input. the connection to the communication partner is not established. A new request may only be initiated when the previous one is ended with DONE_NDR or ERROR. data is received from the client and discarded. TSEND or TRCV is running. You can find further information in section 5 “Licensing”. LICENSED If this output is TRUE. then the Modbus block is licensed on this CPU. In the operating mode S7 is server. BUSY If this output is TRUE. Manual edition 2. If CONN_ESTABLISHED is set to FALSE. the connection establishment is carried out first and then the data transfer takes places. one of the T functions TCON. START_ADDRESS. DATA_TYPE. With the registration key REG_KEY the block MODBUSPN is licensed and the Modbus communication runs without any restraint. Telegrams from the client can be received. With a FALSE signal at the input and an established connection. DISCONNECT In the operating mode S7 is client. This parameter is a runtime parameter and can be set optionally according to your requirements. CONN_ ESTABLISHED CONN_ESTABLISHED indicates that a connection to the communication partner is established and data can be transferred. If the connection is not established (CONN_ESTABLISHED = FALSE). If the connection is not established (CONN_ESTABLISHED = FALSE). the connection establishment is activated. REG_KEY The block MODBUSPN must be licensed for each CPU individually to permit a correct program sequence. TI and WRITE_READ. TDISCON.4 6-9 . the connection may be terminated depending on the parameter DISCONNECT. When the parameter ENQ_ENR turns from TRUE to FALSE. the parameter DISCONNECT = TRUE indicates that the connection is terminated after the completed data transfer. The request telegram is generated with the values of the input parameters UNIT. LENGTH. the parameter DISCONNECT = TRUE indicates that the connection is terminated when the parameter ENQ_ENR is set to FALSE.

The error numbers are described in section 7 and in the STEP7 online help of the functions TCON. After start-up of the PLC an 18 character string is displayed. In the parameters UNIT. which can be read by means of a variable table? You can find further information in section 5 “Licensing”. TSEND and TRCV. an error was detected at a request telegram of the client or when sending a response telegram. TDISCON. With a reading function. the response data from the server has already been entered into the DB. In the operating mode S7 is Client.4 6-10 . DATA_TYPE. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. The output is set with the received value when the job is finished without an error. IDENT_CODE With the identification string IDENT_CODE you can order the registration key at IT4industry. this output indicates a telegram exchange without errors. the parameter UNIT is an output parameter. the activated request was executed without an error. START_ADDRESS. LENGTH. In mode S7 is Server. In the operating mode S7 is Server. Manual edition 2. the parameter UNIT is an input parameter. The error numbers are described in section 7. With a writing function. These outputs are only available and valid as long as DONE_NDR is TRUE. STATUS_MODBUS When ERROR is TRUE. an error was recognized. Status information like “job processing active” is provided by STATUS_CONN as well. The error number is displayed in the STATUS_MODBUS or STATUS_CONN output. which caused the error occurred. In the operating mode S7 is Server. This input has to be set according to your requirements. the ERROR bit is set to FALSE. STATUS_CONN When ERROR is TRUE. the response to the request telegram has been received from the server. STATUS_FUNC This parameter shows the name of the function. the STATUS_MODBUS output displays the error number regarding the processing of Modbus telegrams. the STATUS_CONN output displays the error number regarding the processing of the T functions. The FB copies this value from the request telegram to the respond telegram. The error number is displayed in the STATUS_MODBUS or STATUS_CONN output. The FB copies this value to the request telegram and verifies when receiving the respond telegram. the activated request was ended with an error. In the operating mode S7 is Client. TI and WRITE_READ the request parameters of the client are displayed. UNIT In mode S7 is Client.Function Block MODBUSPN DONE_NDR The parameter DONE_NDR indicates an error-free execution of the request. In this case. ERROR When this output is set.

a maximum of 123 registers or 1968 bits is possible.Function Block MODBUSPN DATA_TYPE The parameter DATA_TYPE defines which Modbus data type is to be accessed with the current job. DATA_TYPE is an input parameter. In the operating mode S7 is Client. In the operating mode S7 is Server. In the operating mode S7 is Server. this is an input parameter. DATA_TYPE is an output parameter. With a writing function. this is an input parameter. all registers or bits have to be in the same DB. In the operating mode S7 is Client. LENGTH The parameter LENGTH specifies the number of MODBUS values that are read or written. With a reading function. In the operating mode S7 is Server.4 6-11 . The following data types are available: Coils Inputs Holding Register Input Register B#16#1 B#16#2 B#16#3 B#16#4 In the operating mode S7 is Client. The different data types are related directly to the used function codes. For each telegram. Data type START_ADDRESS DATA_ TYPE Function Length single_ write Function code Coils 1 read any irrelevant 1 Coils 1 write 1 TRUE 5 Coils 1 write 1 FALSE 15 Coils 1 write >1 irrelevant 15 Inputs 2 read any irrelevant 2 Holding Register 3 read any irrelevant 3 Holding Register 3 write 1 TRUE 6 Holding Register 3 write 1 FALSE 16 Holding Register 3 write >1 irrelevant 16 Input Register 4 read any irrelevant 4 The parameter START_ADDRESS specifies the first MODBUS address that is read or written. this is an output parameter. a maximum of 125 registers or 2000 bits is possible per telegram. this is an output parameter. Manual edition 2. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.

for example. Sometimes the register or bit address is defined as the address of the application layer and in other manuals it is the actually transferred address. The value TRUE specifies the writing mode. e. this is an input parameter. The FB MODBUSPN uses the register or bit address transferred for its parameters start_x. TI In the operating mode S7 is Client. If the value of the input/output is FALSE. MODICON PLCs. Manual edition 2. The Holding Register with offset 0. this is an input parameter. In the operating mode S7 is Client. A potential source of confusion is the varying interpretation of the register address in different manuals. the reading mode is specified. In the operating mode S7 is Server. reference 0001).Function Block MODBUSPN The parameter TI (Transaction Identifier) is copied by the server from the request telegram to the respond telegram according to the MODBUS specification. this is an output parameter. The FB MODBUSPN can only perform this function properly if the TI is changed with each transaction.3 Example of Address Mapping Interpretation of MODBUS Register Addresses The MODBUS data model is based on a series of storage areas with distinct properties. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. 6. Therefore. Only a change of the TI ensures a reliable operation of the FB. Some systems. end_x und START_ADDRESS. The Transaction Identifier is used for the identification of telegrams and the unambiguous allocation of the requests to the corresponding responds. we recommend increment the TI by 1 with any request. WRITE_READ This parameter defines whether a reading or writing function is to be carried out. The FB copies this value to the request telegram and verifies it when receiving the respond telegram. The FB copies this value from the request telegram into the respond telegram. is called 40001 (memory type 4xxxx. Therefore. distinguish these areas by the register or bit addresses.4 6-12 .g. it is possible to use register or bit addresses from von 0000H to FFFFH for each function code. this is an output parameter. In the operating mode S7 is Server.

The Modbus addresses printed in black refer to the Data Link Layer and the ones printed in grey refer to the Application Layer. The diagram is based on the parameterization in the table above. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Manual edition 2. you can find the Modbus register numbers printed in grey. Additionally.Function Block MODBUSPN Example: Parameterization of the Memory Areas Address Mapping data_type_1 db_1 start_1 end_1 data_type_2 db _2 start _2 end _2 data_type_3 db _3 start _3 end _3 data_type_4 db _4 start _4 end _4 data_type_5 db _5 start _5 end _5 data_type_6 db _6 start _6 end _6 data_type_7 db _7 start _7 end _7 data_type_8 db _8 start _8 end _8 B#16#3 W#16#B W#16#1 W#16#1F4 B#16#3 W#16#C W#16#2D0 W#16#384 B#16#4 W#16#D W#16#2D0 W#16#3E8 B#16#0 0 0 0 B#16#1 W#16#E W#16#280 W#16#4E2 B#16#2 W#16#F W#16#6A4 W#16#8FC B#16#1 W#16#10 W#16#6A4 W#16#8FC B#16#0 0 0 0 Holding Register DB 11 Start address: 1 End address: 500 Holding Register DB 12 Start address: 720 End address: 900 Input Register DB 13 Start address: 720 End address: 900 Not used 0 0 0 Coils DB 14 Start address: 640 End address: 1250 Inputs DB 15 Start address:1700 End address: 2300 Coils DB 16 Start address: 1700 End address: 2300 Not used 0 0 0 The following diagram shows a comparison of the SIMATIC memory area and the Modbus-typical register oriented storage arrangement. The SIMATIC addresses printed in black are the offset in the DB.4 6-13 .

....1 641 0 .0 720 + 2... 1000 + 0...0 2300 10001 .0 1700 + 0. +996.0 01251 0 40001 1 40002 1000 31001 1001 31002 .. Inputs (from 10001) +560.0 899 900 40901 +360.. 720 30721 721 30722 .0 2300 DB 13 + 0. 720 . 1700 +74...0 900 901 40902 MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02....Function Block MODBUSPN SIMATIC Modbus device DB 14 Coils (from 00001) + 0.. +358..0 720 + 2. 40721 ...1 1701 .7 2299 +75. +76..2 00001 1250 640 00641 641 00642 DB 16 ..0 640 + 0. .7 2299 +75...0 721 2301 02302 Input Register (from 30001) 0 30001 1 30002 .. 499 40500 500 40501 501 40502 ...0 2300 DB 15 + 0... Holding Register (from 40001) 1 02301 ..0 1700 + 0.0 721 0 1700 11701 1701 11702 . .1 1701 1250 .. +74. + 0. Manual edition 2.. DB 11 01701 ..0 500 DB 12 + 0...0 499 +998.4 6-14 .0 2 . 2300 12301 2301 12302 + 2.

Required memory of the instance-DBs: Instance-DB work memory load memory MODBUSPN ca. Parameter DB The connection. These variables are remanent and keep their validity between FB calls. 2 kByte Local Variables The FB requires 78 bytes of local variables. The instance data block contains parameters of the types input. uses the blocks TSEND and TRCV of the standard library for the data transfer between the PLC and the communication partner.4 6-15 . output and input/output as well as static variables required for its execution.and Modbus-specific parameters are stored in the parameter data block MODBUS_PARAM. That is a total of max. Standard FBs for Connection Handling The function block TCP_COMM. MOD_CLI (52 Byte) or MOD_SERV (28 Byte) and TCP_COMM require 2 bytes local variables and TCON. called by MODBUSPN. Manual edition 2.4 Data and Standard Functions used by the FB Instance DB The function block MODBUS stores its data in an instance DB. 1 kByte ca. MODBUSPN: SFCs for Miscellaneous Functions The FB MODBUSPN uses the following SFCs from the standard library: • FC10 • SFC6 “RD_SINFO“ • SFC20 “BLKMOV” • SFC24 “TEST_DB” • SFC51 “RDSYST” • SFC52 “WR_USMSG” “EQ_STRING” MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Standard FBs for Data Transfer The function block TCP_COMM. uses the blocks TCON and TDISCON of the standard library to establish and terminate the connection between the PLC and the communication partner. Timers The FB does not use any timers. This instance DB is created by STEP7 when initially calling the FB. Flags The function block does not use any flags. TDISCON. TSEND or TRCV use up to 28 bytes depending on the used function block. Additionally. called by MODBUSPN. 160 bytes of local data for one FB MODBUSPN call.Function Block MODBUSPN 6. The variables control the internal process flow of the FB.

5 • SFC20 „BLKMOV“ • SFC24 “TEST_DB” • SFB4 „TON“ Renaming Standard Functions Inducement If the numbers of the standard functions are already assigned within your project or if the number interval is reserved for a different application. MOD_CLI. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. FB64. Manual edition 2. Exemplification: The call hierarchy in MODBUSPN: FB63 TSEND FB104 MOD_CLI FB102 MODBUSP FB64 TRCV FB103 TCP_COMM FB65 TCON FB105 MOD_SERV FB66 TDISCON Rewiring FB65 is possible: FB104 MOD_CLI FB103 TCP_COMM FB65 TCON Internally. SFC20. FB65 and FB66 of FB TCP_COMM or the function blocks MODBUSPN. Behavior A set of rules concerning the function block numbering have to be considered when rewiring function blocks in SIMATIC STEP 7 Manager: When rewiring a function block make sure that the previous function blocks in the call hierarchy have descending numbers. SFC52 and SFB4. It is not possible to rename the system functions SFC6. SFC51. which then calls FB65.Function Block MODBUSPN MOD_CLI and MOD_SERV: SFCs for Miscellaneous Functions The FBs MOD_CLI and MOD_SERV use the following SFCs from the standard library: TCP_COMM: SFCs for Miscellaneous Functions The FB TCP_COMM uses the following SFB from the standard library in addition to the T-blocks: 6.4 6-16 . MOD_SERV und TCP_COMM. SFC24. it is possible to rename the internally called function blocks FB63. function block FB104 calls function block FB103. In this line-up it is possible to rewire FB65 since it is called by TCP_COMM (FB103) which has a smaller function block number than MOD_CLI (FB104).

Call the function "Extras > Re-wire" in the SIMATIC Manager. Manual edition 2. function block FB102 calls function block FB104. add the modifications in the symbolism table supplementary.Function Block MODBUSPN Rewiring FB103 is not possible: FB102 MODBUSPN FB104 MOD_CLI FB103 TCP_COMM Internally. it is necessary to temporarily assign a higher function block number to MODBUSPN (FB102) than MOD_CLI (FB104) has. Afterwards MODBUSPN can have its original name reassigned. in order to re-wire the operands into free areas. though. In this line-up it is not possible to rewire FB103. 4. 2. To be able to keep on using the symbolism diagnostics tools.4 6-17 . which then calls FB103. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. 3. Renaming To rename the blocks proceed as described subsequently: 1. The modifications can be verified by clicking "Extras > Reference data > Display". since the function block MOD_CLI (FB104) has a higher function block number than MODBUSPN (FB102). After this step rewiring TCP_COMM (FB103) will be possible. Solution: If FB103 is to be rewired. Get the information about the used operand by clicking "Extras > Reference data > Display". This is not necessary. Set the operand priority in the object properties of the block folder to "Absolute value".

which caused the error at STATUS_MODBUS or STATUS_CONN. Manual edition 2.4 7-1 . The display elements provide an overview of internal errors. The STATUS parameters can be evaluated in the user program. STATUS Outputs of the FB MODBUSPN For an error diagnosis. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Display Elements (LED) The display elements inform you about the operating mode or about the error conditions of the PLC. When reading the STATUS_MODBUS output. you are provided with a general indication of errors that occurred during the telegram processing and connection handling. When reading the STATUS outputs. The STATUS_CONN output displays status information and error codes with regard to the processing of the T functions. you are provided with a general indication of errors that occurred during the Modbus-specific telegram processing. external errors and interface-specific errors. The output STATUS_FUNC shows the name of the function. The following diagnostic features are available: • Diagnosis via the display elements of the PLC • Diagnosis via the STATUS_MODBUS and STATUS_CONN output of the MODBUSPN function block.Diagnosis 7 Diagnosis Diagnostic Function The diagnostic functions of the PN PLC enable a fast localization of errors. the MODBUSPN function block has 3 STATUS outputs.

RX/TX a telegram is transferred via the integrated interface A detailed description of the display elements can be found in the device manual of the PLC. • Special Displays PN CPU 300. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. There are two types of display functions: • Group Error Displays PN CPU 300 . Manual edition 2.1 Diagnosis via the Display Elements of the PLC Display Functions The display elements of the PLC provide information on the status of the component. PN-CPU 400 .INTF Internal error When this LED is flashing. You can find further information in section 5 “Licensing”.4 7-2 . the Modbus block has not been licensed yet.Diagnosis 7.SF Group error When this LED is flashing. the Modbus block has not been licensed yet. PN CPU 400 and IM 151-8 PN/DP CPU: . You can find further information in section 5 “Licensing”.

The DB number must not be 0 and/or identical to the number of MODBUS_PARAM or the instance DB. • Receipt of the response telegram within the monitoring time The monitoring time can also elapse if less data than specified in the MODBUS telegram header is received. At least the first area (_1) has to be parameterized. (x = 1 to 8) 1. Subsequent errors with loss of telegrams can occur. end_x. Test end_x >= start_x 5. Modbus addresses for the same data type defined in two db_x lead to an error message (address overlap). In the cyclical operation no requests are executed. Errors during start-up provoke the ERROR bit to remain set.2 Verification by the FB MODBUSPN During Start-up • Unambiguousness of the id parameter in the connection parameters of DB MODBUS_PARAM • Parameter group data_type_x. Validity check of data_type_x 3. db_x. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. With data_type_x = 0 the Modbus area is disabled and not further verified. A correction of the parameterization and a STOP Æ RUN transition of the PLC are necessary. Manual edition 2.Diagnosis 7. there also is a check whether the data block specified by the register or bit address is available and has the necessary length. start_x. 2. db_x <> 0 4.4 7-3 . Cyclical Operation S7 is Client Verification when the FB is called: • Valid registration key • DB MODBUS_PARAM is available with the necessary length • Range of values monitoring time RECV_TIME and CONN_TIME • Range of values START_ADRESS • Range of values LENGTH • When executing a request.

an exception telegram is sent. the length in the header of the response telegram is checked for plausibility regarding the request. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Manual edition 2. The DB number must not be 0 or identical to the number of MODBUS_PARAM or the instance DB. the length in the header. • The number of registers or bits is verified. • FC 5 or FC6: Echo in the respond is equal to the request • Valid registration key • Receipt of the second part of the request telegram within the monitoring time The monitoring time can also elapse if less data than specified in the MODBUS telegram header is received. • Protocol identifier = 0 • Length is between 3 and 253 Additionally. If the function code is not equal to 1. • Protocol Identifier = 0 • Length between 6 and 207 • Received function code is verified. • Sent UNIT is equal to the received one • Sent FC is equal to the received one • Response is an exception code telegram • For write requests. 15 or 16 an exception telegram is sent. 2. an exception telegram is sent. the number of registers or bits and the byte count in the telegram must match. 4.4 7-4 . 6. • For write requests. there is also a check whether the data block specified by the register or bit address is available and has the necessary length. • During the execution of a request. In case of an error. 3.Diagnosis Verification in the response telegram: Cyclical Operation S7 is Server • Received transaction identifier is equal to the sent one. the start address and number of registers/bits have to match with the request telegram. Subsequent errors with loss of telegrams can occur. If the number is too large. 5.

the FB terminates the connection: • Monitoring time for connection establishment exceeded • Monitoring time for receive exceeded • PI <> 0 • received TI different to sent TI • Length in the header does not match the length information in the telegram MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Manual edition 2.4 7-5 .Diagnosis Termination of the Connection in Case of Error In special error situations.

STATUS is valid when ERROR is TRUE. FB63. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Correct the parameterization in DB MODBUS_PARAM A003 The DB to which MODBUS addresses shall be mapped is too short. S7 is Server: Modify the request of the client. Minimum length: . Correct the parameters. please consult the diagnosis buffer or the online help of the SIMATIC Manager. called by MOD_CLI or MOD_SERV.register values (end_x . The block TCP_COMM.3 Diagnosis Messages of the FB MODBUSPN Messages at the STATUS Outputs of the FB The block MOBUSPN has 3 status outputs: STATUS_MODBUS.start_x + 1) * 2 . SFC24. The S7 sends an exception telegram. Error Messages of the called SFCs and FBs The FBs MODBUSPN. Error messages of FB MODBUSPN at the output STATUS_MODBUS STATUS Event text Remedy (Hex) A001 The parameter data block MODBUS_PARAM is too short. STATUS_CONN and STATUS_FUNC. For further details on the error messages. SFC20. SFC51 und SFC52. whereas STATUS_CONN displays the error numbers regarding the connection handling. STATUS_MODBUS displays the error numbers regarding the processing of Modbus telegrams. FB64. Below you can find a list of FB-specific error messages. FB65 and FB66. Applies only if S7 is client: An invalid combination of DATA_TYPE and WRITE_READ is given. The error messages of these blocks are passed on to STATUS_CONN without any changes. S7 is Client: Correct the parameters START_ADDRESS or LENGTH Other possible reasons: A004 • S7 is client: Wrong initialization parameter • S7 is server: Wrong address area in the request telegram of the client. STATUS_FUNC shows the name of the function. which caused the error. The error messages of these blocks are passed on to STATUS_MODBUS without any changes. uses the standard blocks SFB4.bit values (end_x . Correct the length of MODBUS_PARAM A002 The parameter end_x is less than start_x. Manual edition 2.4 7-6 .Diagnosis 7.start_x ) / 8 + 1 Extend the DB. MOD_CLI and MOD_SERV use the standard functions SFC6. Only data type 1 or 3 can be written.

The connection is terminated. 5. A00C The received byte count does not match the number of registers. S7 is Client: Correct the parameter LENGTH. Verify the data of the communication partner with the help of a telegram trace. 15 and 16. S7 is Server: The number of registers/bits in the request telegram is invalid. 2. S7 is Server: Modify the request of the client or correct the parameterization of data_type_x. Verify the data of the communication partner with the help of a telegram trace. S7 is Client: Correct the parameter combination DATA_TYPE. START_ADDRESS and LENGTH does not exist in data_type_1 to data_type_8. The S7 sends an exception telegram. 3. 4. The connection is terminated. A00E The length indicated in the MODBUS-specific telegram header does not match the number of registers/bits or the byte count in the telegram. A00D Only if S7 is client: The register or bit address respectively the number of registers or bits in the response telegram is not equal to the one in the request telegram. The RECV_TIME has to be at least 20 ms. A00A Only if S7 is client: The received UNIT is not equal to the sent one. The S7 sends an exception telegram. The FB ignores all data. A007 Only if S7 is client: An invalid monitoring time RECV_TIME or CONN_TIME is parameterized. S7 is server: The S7 sends an exception telegram. START_ADDRESS. LENGTH.4 7-7 . Range of values: Read coils/inputs: 1 to 2000 Write coils: 1 to 1968 Read registers: 1 to 125 Write holding registers: 1 to 123 A006 The given range of registers defined with DATA_TYPE. S7 is client: Verify the data of the communication partner with the help of a telegram trace.Diagnosis Error messages of FB MODBUS MODBUSPN at the output STATUS_MODBUS STATUS Event text Remedy (Hex) A005 S7 is client: An invalid value for the parameter LENGTH is given. 6. A00B S7 is client: Received function code is not equal to the sent one. The connection is terminated. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. CONN_TIME 100ms Correct the parameterization. S7 is server: An invalid function code was received. S7 is server: The FB MODBUS only supports the function codes 1. S7 is Server: Modify the number in the request telegram. Manual edition 2. A009 Only if S7 is client: The received transaction identifier TI is not equal to the sent one.

DB 0 can’t be used. A015 The parameterized areas data_type_1 and data_type_5 overlap. The connection is terminated. A028 The parameterized areas data_type_2 and data_type_5 overlap. The connection is terminated. Correct the parameterization in DB MODBUS_PARAM. A027 The parameterized areas data_type_2 and data_type_5 overlap. A011 An invalid value for DATA_TYPE is given (Value range: 1 Correct the parameters. A012 The parameterized areas data_type_1 and data_type_2 overlap.Diagnosis Error messages of FB MODBUSPN at the output STATUS_MODBUS STATUS Event text Remedy (Hex) A00F A protocol identifier <> 0 was received.4 7-8 . to 4). Verify the data of the communication partner with the help of a telegram trace. Correct the parameterization in DB MODBUS_PARAM A024 The parameterized areas data_type_2 and data_type_4 overlap. A019 0 is assigned to one of the parameters db_x while the according data_type_x is <> 0. Correct the parameterization in DB MODBUS_PARAM. A014 The parameterized areas data_type_1 and data_type_4 overlap. The data areas must not contain any overlapping register areas. A034 The parameterized areas data_type_3 and data_type_4 overlap. Correct the parameterization in DB MODBUS_PARAM. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. A026 The parameterized areas data_type_2 and data_type_5 overlap. A016 The parameterized areas data_type_1 and data_type_6 overlap. A023 The parameterized areas data_type_2 and data_type_3 overlap. A018 The parameterized areas data_type_1 and data_type_8 overlap. A01A Wrong length in the Modbus header (1 to 253 byte are valid). A01F The FB MODBUSPN has turned to an invalid state. Please contact the product support. Verify the data of the communication partner with the help of a telegram trace. it is reserved for system functions. Manual edition 2. The data areas must not contain any overlapping register areas. A017 The parameterized areas data_type_1 and data_type_7 overlap. A013 The parameterized areas data_type_1 and data_type_3 overlap. A025 The parameterized areas data_type_2 and data_type_5 overlap. A010 In the parameters db_1 to db_8 a DB number is used twice.

A056 The parameterized areas data_type_5 and data_type_6 overlap.4 7-9 . A07F The data block defined at DB_PARAM is no parameter DB for Modbus communication. A048 The parameterized areas data_type_4 and data_type_8 overlap. Correct the parameterization in DB MODBUS_PARAM A036 The parameterized areas data_type_3 and data_type_6 overlap. A078 The parameterized areas data_type_7 and data_type_8 overlap. A079 The connection ID of parameter ID is not defined in DB MODBUS_PARAM. A046 The parameterized areas data_type_4 and data_type_6 overlap. A067 The parameterized areas data_type_6 and data_type_7 overlap. A037 The parameterized areas data_type_3 and data_type_7overlap. Correct the parameterization in DB MODBUS_PARAM. The value range is 0 to 4. A07E The DB number of db_x is identical to the number of the parameter DB MODBUS_PARAM or to the instance DB. A057 The parameterized areas data_type_5 and data_type_7 overlap. The length information in DBW0 was changed or a wrong DB was defined. A058 The parameterized areas data_type_5 and data_type_8 overlap. A047 The parameterized areas data_type_4 and data_type_7 overlap. A07D Parameter data_type_1 is not defined. The data areas must not contain any overlapping register areas. A07B The parameter ID exists twice in the parameter DB. The parameter area _1 is the default area and must be defined. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. A045 The parameterized areas data_type_4 and data_type_5 overlap. A038 The parameterized areas data_type_3 and data_type_8overlap. A068 The parameterized areas data_type_6 and data_type_8 overlap. A07C An invalid value data_type_x was given.Diagnosis Error messages of FB MODBUSPN at the output STATUS_MODBUS STATUS Event text Remedy (Hex) A035 The parameterized areas data_type_3 and data_type_5 overlap. Range of values is 1 to 4095. Correct the parameterization at the input ID. Manual edition 2. A07A An invalid value ID is parameterized.

A095 An exception telegram with an unknown exception code was received (only if S7 is client). This is a status information. A084 The character string for identification “IDENT_CODE” could not be determined.Diagnosis Error messages of FB MODBUSPN at the output STATUS_MODBUS STATUS Event text Remedy (Hex) A080 The parameter DB_PARAM was changed without a restart of the CPU. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. doesn’t support the requested length). A082 Only if S7 is client and function code 6: The received register value is not equal to the sent one. Verify the project if there is any invalid write access to the license DB. A094 An exception telegram with exception code 4 was received (only if S7 is client) The communication partner is in a state. The Modbus communication runs without a license as well.g. A092 An exception telegram with exception code 2 was received (only if S7 is client) Correct LENGTH or START_ADDRESS at the call of the FB. See also section 5 “Licensing”. Read the identification string IDENT_CODE for this CPU and order the registration key at IT4industry. The bit ERROR is not set. A093 An exception telegram with exception code 3 was received (only if S7 is client) The communication partner can’t process the received request (e. Check the error message of the communication partner and verify the data with a telegram trace if needed. in which the received request can’t be processed. Please contact the Product Support. A090 The block MODBUSPN is not licensed for this CPU. Wait with the initiation of a new request until the previous one was finished either with DONE/NDR = TRUE or ERROR = TRUE. A081 Only if S7 is client and function code 5: The received coil status is not equal to the sent one. Please contact the Product Support. A091 An exception telegram with exception code 1 was received (only if S7 is client) The communication partner does not support the requested function. Restart the CPU after changing this parameter. Verify the data of the communication partner with the help of a telegram trace.4 7-10 . DB_PARAM is an initialization parameter. An attempt to an invalid or non existing address at the communication partner was made. Manual edition 2. A085 An error occurred during the license handling. Verify the data of the communication partner with the help of a telegram trace. A083 Only if S7 is client: A request was initiated prior to the completion of the previous one.

Diagnosis Error messages of FB MODBUSPN at the output STATUS_CONN STATUS Event text Remedy (Hex) A100 The monitoring time CONN_TIME or RECV_TIME was exceeded when executing a job. A101 The monitoring time of the TDISCON is exceeded. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Manual edition 2. Please contact the product support. Check the parameterization of the connection.4 7-11 . When RECV_TIME is exceeded. the connection is terminated.

when FB MODBUSPN is called with different instance DBs in OB1 or cyclic interrupt OB and OB100.Diagnosis 7. All data blocks that are specified in DB_x must be created and copied into the PLC. FB 64. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Manual edition 2. 80B1 The DB does not exist in the PLC. This error code is also reported. Use the same IDB for the call of MODBUSPN in OB1 or cyclic interrupt OB and OB100. See online help (SIMATIC manager -> mark block -> key F1) 8xxx For detailed information please refer to the online help of SIMATIC Manager.4 7-12 . See online help (SIMATIC manager -> mark block -> key F1) Error messages of FB 63.5 Diagnosis Messages of SFC24 Error messages of SFC24 at the output STATUS_MODBUS STATUS Event text Remedy (Hex) 80A1 DB Number = 0 or too large for the PLC Choose a valid DB number.4 Diagnosis Messages of Called Blocks Error messages of SFC 6 and SFC 20 at the output STATUS_MODBUS STATUS Event text Remedy (Hex) 7xxx For detailed information please refer to the online help of SIMATIC Manager. See online help (SIMATIC manager -> mark block -> key F1) 8xxx For detailed information please refer to the online help of SIMATIC Manager. FB 65 and FB 66 at the output STATUS_CONN STATUS Event text Remedy (Hex) 7xxx For detailed information please refer to the online help of SIMATIC Manager. See online help (SIMATIC manager -> mark block -> key F1) 7. 80B2 DB UNLINKED DB must not be created as UNLINKED.

Manual edition 2. Please note. It displays the handling of the Modbus blocks and is not to be understood as a solution for a customer-specific installation configuration. • Simatic Station is S7-300. Example Project on the CD On the CD you can find an extensive example project which offers all varieties of parameterization possibilities for the Simatic stations. S7-400 or IM 151-8 PN/DP CPU • Simatic Station is client or server MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.4 8-1 . the provided example project is meant for information purposes only.Application Sample 8 Sample Application General Information The following simple programming example illustrates the use of FB MODBUSPN.

Application Sample Sample Program The programming example consists of the blocks: • Start-Up OB100 with call of FB102 • Programming error OB121 • Cyclic program processing OB1 with call of FB102 • Global DBs for job trigger (e. Block Symbol Comment OB 1 CYCL_EXC cyclic program processing OB 100 COMPLETE RESTART start-up OB for restart OB 121 PROG_ERR programming error OB FB 102 MODBUSPN FB MODBUSPN FB 103 TCP_COMM FB TCP_COMM FB 104 MOD_CLI FB MOD_CLI FB 105 MOD_SERV FB MOD_SERV DB 1 CONTROL_DAT work DB CONTROL DAT for FB MODBUSPN DB 2 MODBUS_PARAM parameter DB PARAM_DB for FB MODBUSPN DB 3 LICENSE_DB license data block for FB MODBUSPN DB 102 IDB_MODBUS instance DB for FB MODBUSPN DB 11 DATA_AREA_1 value DB for area 1 DB 12 DATA_AREA_2 value DB for area 2 DB 13 DATA_AREA_3 value DB for area 3 DB 14 DATA_AREA_4 value DB for area 4 DB 15 DATA_AREA_5 value DB for area 5 MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Manual edition 2.4 8-2 .g. with variable table) and for licensing • Data blocks for register and bit values Used Blocks The following blocks are used in the provided sample project for S7 stations with FB MODBUSPN.

December 28. Manual edition 2. 2006 http://www.org MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.4 Appendix .modbus-IDA.1b.A Literature MODBUS IDA MODBUS APPLICATION PROTOCOL SPECIFICATION V1.1 .

B Baud Rate . the operand stored there can be directly accessed. Communications Processor Communications processors are modules for point-to-point connections and bus connections.> transmission rate Block Call A block call occurs when program processing branches to the called block Block Parameter Block parameters are variables within multiple-use blocks. Segments are transparent for addressing. FC. Module for communications tasks. in general terms. CP Communications Processor. With the help of a connection ID the system function blocks can communicate between two communication points. OB. an object that requests a service from a -> server. Subnets can consist of bus segments and connectivity devices such as repeaters and bridges. SDB) • User-defined data types (UDT) Part of a -> subnet. Blocks Blocks are elements of the user program which are defined by their function. Manual edition 2. or purpose. With STEP7 there are Bus Segment • Code blocks (FB. Automation System An automation system is a programmable logic controller that contains at least a PLC. Configuration The configuration is the set up of individual modules of the PLC in the configuration table. Connection Parameterization The specification of a connection ID in the system function block. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. structure. different input and output devices as well as HMI devices.4 Glossary . SFC) • Data blocks (DB. If the address is known.Glossary A Address The address identifies a physical storage location. SFB.1 . C Client A client is a device or. which are replaced with actual values when the relevant block is called.

operating system. in accordance with the IEC standard.2 . memory. Manual edition 2. D Data Block (DB) These are blocks containing data and parameters with which the user program works. Diagnostic Functions The diagnostics functions cover the entire system diagnosis and include detection. They are classified into elementary and structured data types. H Hardware Hardware is the term given to all the physical and technical equipment of a PLC. Data Type Data types allow users to define how the value of a variable or constant is to be used in the user program. for example.4 Glossary . code blocks) from the programming device into the load memory of the PLC. errors on a module or system errors in the PLC. The memory for the function block is an assigned data block.CPU Central processing unit of the S7 programmable logic controller with control and arithmetic unit. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. Download Downloading means loading objects (e. and interfaces to I/O modules. Default Setting The default setting is a basic setting which is always used if no other value is specified. analysis and reporting of errors within the automation system. the user program is executed in a constantly repeating program loop. say. Complex data can be stored in structured form. a program error or by operating mode transitions. The data held in the data blocks can be accessed absolutely or symbolically. called a cycle. They are subdivided into global data blocks and instance data blocks. are ”blocks with memory”.g. Unlike all other blocks. Function blocks can be parameterized but can also be used without parameters. a so called ”instance data block”. Diagnostic Event Diagnostic events are. Cyclic Program Processing In cyclic program processing. which are caused by. CRC Cyclic Redundancy-Check = Checksum which guarantees a high probability of error recognition. F Function Block (FB) Function blocks are components of the user program and. Cycle Time The cycle time is the time the PLC needs to execute the user program once. in which detailed information on diagnostic events are stored in the order in which they occur. Diagnostic Buffer Every PLC has a diagnostic buffer. data blocks do not contain instructions.

MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.4 Glossary . Interface Module On the interface module the physical conversion of signals takes place. Module Modules are pluggable printed circuit boards for programmable logic controllers Module Parameters Module parameters are used to set the module behaviors.I Industrial Ethernet A LAN system complying with IEEE 802. Online Help STEP7 allows you to display contextual help texts on the screen while working with the programming software. Operating System of the PLC The operating system of the PLC organizes all functions and operations of the PLC which are not connected to a specific control task. Interrupt Interrupt is a name for a break of the program processing in the processor of an automation system by an external alarm. Operating Mode The SIMATIC S7 programmable controllers have three different operating modes: STOP. Media Access Control (MAC) Mechanisms for controlling access by a station to a common transmission medium shared with other stations. Offline means that no such data connection exists. It can be both absolutely and symbolically addressed. N NCM S7 for Industrial Ethernet Configuration software for configuration and diagnostic functions on an Ethernet CP. START UP and RUN.3 (ISO 8802-2) Instance Data Block An instance data block is a block assigned to a function block and contains data for this special function block. By exchanging the pluggable interface module you can adapt the communications processor to the physical interface of the communications partner.3 . M MAC-Address Address to distinguish between different stations connected to a common transmission medium (Industrial Ethernet). O Online / Offline Online means that a data connection exists between PLC and programming device. The functionality of the PLCs varies in the individual operating modes. A distinction is made between static and dynamic module parameters. Manual edition 2. Operand An operand is part of a STEP7 instruction and states with what the processor is to do something.

System Function Block (SFB) System function blocks are software modules with memory which are already integrated into the operating system of the S7-PLC and can be called up by the user as required. A subnet consists of several stations with unique -> MAC addresses. System Block System blocks differ from the other blocks in that they are already integrated into the S7-400 system and are available for already defined system functions. A distinction is made between block parameters and module parameters. Parameterization Parameterization means setting the behavior of a module. START UP The operating mode START UP is active when the PLC transits from operating mode STOP to operating mode RUN.P Parameter Parameters are values that can be assigned. system functions. System Function (SFC) System functions are software modules without memory which are already integrated into the operating system of the S7-PLC and can be called by the user as required. At the beginning of the cyclic program. Manual edition 2. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02. These include the operating system and the user programs. be connected together by -> gateways to form a network. Process image This is a special memory area in the PLC.4 Glossary . They are classified into system data blocks. for example. Procedure The execution of a data interchange operation according to a specific protocol is called a procedure. These rules are called protocols. the signal states of the input modules are transferred to the process image input table. At the end of the cyclic program. A system consists of several subnets with unique subnet numbers. S Server A server is a device. The subnet includes bus components and all the attached stations. and system function blocks. Subnets can. an object that provides certain services.4 . A service is started at the instigation of a -> client. Software Software is the term given to all programs used on a computer system. the process image of the outputs is transferred to the output modules as output signals. R Rack A rack is a rail containing slots for mounting modules. STEP7 STEP7 is the programming software of SIMATIC S7. or in general terms. Subnet A subnet is part of a -> network whose parameters must be matched. Protocol The communications partners involved in a data interchange must abide by fixed rules for handling and implementing the data traffic.

V Variable A variable is an operand (e. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.g. code blocks) from the load memory of the PLC into the programming device. The user program for SIMATIC S7 is structured and is divided into smaller units called blocks. E 1.g.T Tool A tool is a piece of software that is capable of accessing operating system functions in a programming device. W Work Memory The work memory is a RAM on the PLC which the processor accesses while processing the user program.5 . Transmission Rate According to DIN 44302. The unit is bps.0) which can have a symbolic name and can therefore also be addressed symbolically. for example the distance across U Upload Uploading means loading objects (e. this is the number of binary decisions transmitted per time unit.4 Glossary . he set or selected transmission rate depends on various conditions. User Program The user program contains all instructions and declarations for signal processing. by means of which a system or a process can be controlled. Manual edition 2.

siemens.Customer Support Siemens AG Industry Sector I IS IN E&C Werner-von-Siemens-Str.industry@siemens. MODBUS / TCP communication via the integrated PN interface of the CPU 2XV9450-1MB02.4 Stand: 02/2010 .com/s7modbus Siemens Aktiengesellschaft Subject to change without prior notice.com http://www. Manual edition 2. 60 91052 Erlangen Tel: ++49 9131 7-46111 Fax: ++49 9131 7-44757 Mail: it4.