Siemens Industry Online Support
Siemens AG
Entry type: Application example Entry ID: 61586633, Entry date: 12/04/2018

Modbus PtP - Standardized communication of PCS 7 with Third-Party Systems

  • Entry
  • Associated product(s)
Modbus is an open communication protocol which is widely used all over the world and supported by many manufacturers.
The interfacing of PCS 7 systems with other systems via Modbus is a useful option, especially when
  • Existing systems are to be expanded or modernized.
  • Controllers and systems from different manufacturers are to be combined – e.g. when new plants are being installed.

Modbus is based on a master/slave or server/client architecture which can be implemented in different ways within the PCS 7 environment. Selection depends, on the one hand, on the individual systems and controllers which shall communicate with each other, since not all controllers and systems support all types of Modbus protocols (PtP or TCP). On the other hand, the type of interfacing also arises from the specific the plant network, i.e. the allocation of communication partners as master or slave.
In the following sections we present you some fully described solutions based on PCS 7 standard functions and add-on products which are suitable to significantly reduce your engineering costs and efforts. You may use them either for new configurations or integrate them in existing projects. All required hardware and software components are Siemens products which, as always, guarantee best compatibility, state-of-the-art technology and upgradability. The PCS 7 standard and the Modbus standard are followed without exception.

This application example is valid for the following PCS 7 versions:

  • PCS 7 V9.0
  • PCS 7 V8.2
  • PCS 7 V8.1
  • PCS 7 V8.0 
  • PCS 7 V7.1

Core topics of this application description
The two solutions described in the following for the configuration and parameterization of Modbus PtP in PCS 7 systems differ with regard to the use of the Modbus functions either as master or slave.

  • PCS 7 Modbus PtP master
  • PCS 7 Modbus PtP slave

Each of these variants is considered under the following aspects

  • Advantages
  • Required hardware and software
  • Installation and setup
  • Configuration
  • Performance data

Furthermore, each solution not only describes the connection to a singular PCS 7 system, but also the connection to a redundant system.
Your benefits at a glance

  • Easy configuration and standardized solutions for the complete lifecycle of the plant
  • Optimized communication performance
  • Minimum recovery time after communication failure
  • Complete block library with help functions in German and English
  • Configuration software with help functions in German and English

  Modbus PtP - Standardized communication of PCS 7 with Third-Party Systems (1,9 MB)

Furthert information
Modbus/TCP - Standardized and redundant Communication of PCS 7 with Third-Party Systems

Last changes
Note on alternative configuration in documentation added.

Additional Keywords
serial communication, coupling, data link, interface, interfacing, link-up, linking, integration


Security information
In order to protect technical infrastructures, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art IT security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about cyber security, please visit