Siemens Simatic ET 200S Operating Instructions Manual page 326

Glossary
Terminal modules
Terminal modules implement the electrical and mechanical connection of the distributed IO
modules with the interface module and the terminating module.
The inserted distributed IO module determines the signals on the terminals of the terminal
module. Depending on the terminal module which has been selected, only certain terminals
are available.
Terminating module
The terminating module completes the ET 200S distributed IO system. If you have not
inserted a terminating module, the ET 200S is not ready for operation.
User data qualifier
Each IO module is assigned a value in the input or output data message; this value makes a
statement on the quality of this user datum. For example, outputs of a specific module can
be switched off by means of this without affecting other modules.
Voltage group
A group of electronic modules supplied by a power module.
Glossary-10
Operating Instructions, 12/2005, A5E00515771-03
ET 200S