Configuring the RS485
For RS485 mode, there is only one operating mode. The different selections for Receive line
initial state reference the cases shown below for more details.
● Half duplex (RS485) two wire mode. In the Receive line initial state:
Case 4: RS485: Forward bias
● Mode of operation: RS485
● Receive line initial state: Forward bias (biased with R(B) > R(A) > 0 V)
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
– Select none when you supply the bias and termination (Case 5).
– Select forward bias to use internal bias and termination (Case 4).
Communication processor and Modbus TCP
12.3 Point-to-point (PtP) communication
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