Siemens SIMATIC RF185C Operating Instructions Manual page 31

Setting up RF18xC/RF18xCI with grounded reference potential
When the communication module is set up with grounded reference potential, any
interference currents that occur are diverted to functional ground. The connections must be
connected externally (connection between 1M and FE).
Setting up RF18xC/RF18xCI with ungrounded reference potential
When the communication module is set up with ungrounded reference potential, any
interference currents occurring are conducted to functional ground via an internal RC
network (no external connection between 1M and FE).
RF18xC/RF18xCI in total configuration
The following figure shows the communication module in its overall electrical design.
①
②
③
④
Figure 5-5
SIMATIC RF185C, RF186C, RF188C, RF186CI, RF188CI
Operating Instructions, 04/2020, C79000-G8976-C512-03
5.2 Operation of the CM on grounded/ungrounded power supply
Main switch
Short-circuit and overvoltage protection
Fuses for line protection (automatic circuit breaker for 16 A)
When setting up the communication module with an ungrounded reference potential, there is
no connection between 1M, 2M, and FE
Electrical design
Connection
31