Signal modules of the SIMATIC S7-400 operated centrally in the automation system have only minor importance in the context of SIMATIC PCS 7. They are only sometimes an alternative to the distributed process I/Os in small applications or plants that are less distributed.
We recommend the following standard process I/Os for the SIMATIC PCS 7 process control system for automation on the field level:
Distributed I/O system ET 200M for high-density applications
Within the ET 200 family, ET 200M embodies the main line of distributed I/O systems for process control applications with SIMATIC PCS 7. It offers a wide range of I/O modules in S7-300 design, including special process control functions:
Standard analog and digital modules
Redundancy-capable I/O modules
I/O modules with enhanced diagnostic capability
Ex I/O modules
Intelligent controller and counter modules
F modules for safety applications
The use of active bus modules enables faulty I/O modules to be replaced during operation (RUN) of the plant without affecting adjacent modules (“hot plug” function). A quick and safe connection of field devices to the I/O modules of remote I/O ET 200M stations can be performed through so-called MTAs (Marshalled Termination Assemblies). They help to significantly reduce the work and costs associated with cabling and commissioning, and avoid wiring mistakes.