Siemens SIMATIC S7-1200 Manual page 336

Technical specifications
A.9 Communication interfaces
CB 1241 RS485 (6ES7 241-1CH30-1XB0)
①
Connect "TA" and TB" as shown to terminate the network. (Terminate only the end devices on the RS485 network.)
②
Use shielded twisted pair cable and connect the cable shield to ground.
You terminate only the two ends of the RS485 network. The devices in between the two end
devices are not terminated or biased. See the S7-1200 System Manual section on "Biasing
and terminating an RS485 network connector"
Table A- 67
Pin
1
2
3
4
5
6
7
8
9
Shell
336
Connector pin locations for CB 1241 RS485 (6ES7 241-1CH30-1XB0)
9-Pin connector
RS485 / Logic GND
RS485 / Not Used
RS485 / TxD+
RS485 / RTS
RS485 / Logic GND
RS485 / 5 V Power
RS485 / Not used
RS485 / TxD-
RS485 / Not Used
X20
--
--
3 - T/RB
1 - RTS
--
--
--
4 - T/RA
--
7 - M
Manual, 03/2014, A5E02486774-AF
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