S7 OpenModbus/TCP

The easy way to interface SIMATIC controls to multi-vendor systems.

The challenge

MODBUS is an open protocol used around the world and supported by many different manufacturers. Along with MODBUS, MODBUS/TCP was developed for use in modern networks. This protocol now ranks as an open Internet draft standard introduced to IETF, the Internet Engineering Task Force responsible for Internet standardization. As a result, manufacturers and users everywhere are free to implement this open protocol, and many leading manufacturers have already taken advantage of this opportunity. With the increasing popularity of Ethernet communications in both industry and offices, MODBUS/TCP is enjoying an increasingly broad use in all industries. In particular heterogeneous system landscapes are typical areas of application.

SIMATIC S7 on MODBUS/TCP networks

Networking SIMATIC S7 to other systems via MODBUS Industrial Ethernet is a very attractive option, especially when

• SIMATIC S7 automation systems are being used to expand or modernize legacy configurations

• controllers and systems from multiple vendors are being networked  (including when constructing new plants)

So far, however, SIMATIC S7 systems didn’t feature MODBUS/TCP for Industrial Ethernet as a standard. Therefore we have now designed an interface solution.

Our solution

MODBUS Versions 

MODBUS block for CPs

This MODBUS version is applicable to SIMATIC S7 300 and 400 PLCs. A CP343-1 or CP443-1 is required for the MODBUS communication.

MODBUS block for PN PLCs

This MODBUS version is applicable to SIMATIC S7 PN PLCs and ET200S PN PLCs. In this case, the integrated PN-interface is used for the MODBUS communication.

MODBUS block with redundancy functionality

This MODBUS version is applicable to SIMATIC S7 400H systems. A CP443-1 is required for every subsystem for the MODBUS communication.

MODBUS block for reading data from PAC devices (with PN PLCs)
This MODBUS version is applicable to SIMATIC S7 PN PLCs and ET200S PN PLCs. In this case, the integrated PN-interface is used for the MODBUS communication. It is possible to read out predefined values of a large number of PAC 3200 devices.

For more information:

•  Catalog ST 80/ST PC 2012

Customer benefits

• Multi-vendor systems can be easily linked to SIMATIC S7 by Industrial Ethernet

• Step-by-step expansion or modernization of legacy systems with the latest SIMATIC technology is highly cost-effective

• You can rely on dependable, Siemens-quality support 

• Using the MODBUS function block requires no specific expertise 

• You benefit from the familiar look and feel of SIMATIC engineering of STEP 7 and PCS 7 

• In the products for PN-CPUs, Wizards are used for configuration

Simple Configuration

Enlarge

The configuration is carried out with the standard tool SIMATIC STEP 7.

For the MODBUS blocks for the PN PLCs, there are the additional options of a Wizard which provides the possibility of a very fast and comfortable configuration.