Siemens SIMATIC S7 System Manual page 461

The CM01 signal board is RS485-compatible. The following table shows the connector that
provides the physical connection for the signal board and describes the pin assignments.
Table 8- 18
Pin number
1
2
3
4
5
6
Note
The CPU models CPU CR20s, CPU CR30s, CPU CR40s, and CPU CR60s do not support
the use of expansion modules or signal boards.
S7-200 SMART
System Manual, V2.3, 07/2017, A5E03822230-AF
Pin assignments for the S7-200 SMART CM01 Signal Board (SB) port (Port 1)
Connector Signal CM01 Signal Board (SB) port (Port 1)
Ground Chassis ground
Tx/B RS232-Tx/RS485-B
Request-to- RTS (TTL)
Send
M-ground Logic common
Rx/A RS232-Rx/RS485-A
+5 V DC +5 V, 100 Ω series resistor
Communication
8.6 RS485
461