Siemens SIMATIC S7 System Manual page 772

Technical specifications
A.8 RS485/RS232 signal boards
Table A- 150 RS232 Transmitter and receiver
Technical data
Transmitter output voltage
Transmit output voltage
Receiver input impedance
Receiver threshold/sensitivity
Receiver input voltage
Isolation
RS232 signal to chassis ground
RS232 signal to CPU logic
common
Cable length, shielded
Table A- 151 Wiring diagram for the SB CM01 RS485/RS232 (6ES7288-5CM01-0AA0)
SB CM01 RS485/RS232 (6ES7288-5CM01-0AA0)
Table A- 152 Connector pin locations for SB CM01 RS485/RS232 (6ES7288-5CM01-0AA0)
Pin
772
SB RS485/RS232
+/-5 V min. at RL = 3K Ω
+/- 15 V DC max.
3 K Ω min.
0.8 V min. low, 2.4 max. high
0.5 V typical hysteresis
+/- 30 V DC max.
None
10 m max.
X20
1 Functional Earth
2 Tx/B
3 RTS
4 M
5 Rx/A
6 5 V Out (Bias Voltage)
System Manual, V2.3, 07/2017, A5E03822230-AF
S7-200 SMART