Siemens SIMATIC PCS 7 Configuration page 30

2 Configuring and wiring
2.3 Redundant connections of the distributed I/O
Example of an SM 331; AI 8x0/4...20 mA HART (2-wire transducer)
Note A 2-wire transducer must be connected and configured to two redundant HART
analog input modules as a 4-wire transducer.
You can find more detailed information in the manual "Distributed I/O Device
ET 200M HART Analog Modules".
The terminals 10 and 11 may not be connected to the front connector
(see Figure 2–12).
Figure 2–14
The interconnected Zener diodes are required if the system is to continue
functioning while dragging a module.
Configuration of Redundant I/O Modules
Entry-ID: 28430682, V2.0, 03/2015
30