Siemens S7-1200 - Page 977

Technical specifications
A.14 Communication interfaces
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
977
Technical data
CM 1241 RS422/485
Isolation
RS485 signal to chassis ground
RS485 signal to CPU logic common
500 VAC, 1 minute
Cable length, shielded
1000 m max. (baud rate dependent)
Baud rate 300 baud, 600 baud, 1.2 kbits, 2.4 kbits, 4.8 kbits, 9.6 kbits (default),
19.2 kbits, 38.4 kbits, 57.6 kbits, 76.8 kbits, 115.2 kbits,
Parity No parity (default), even, odd, Mark (parity bit always set to 1),
Space (parity bit always set to 0)
Number of stop bits
1 (default), 2
Flow control
XON/XOFF supported for the RS422 mode
Wait time
0 to 65535 ms
Table A- 255 Power supply
Technical data
CM 1241 RS422/485
Power loss (dissipation)
1.1 W
From +5 VDC
220 mA
Table A- 256 RS485 or RS422 connector (female)
Pin
Description
Connector
(female)
Pin
Description
1
Logic or communication ground
6 PWR
+5 V with 100 ohm series resistor: Output
2 TxD+
1
Connected for RS422
Not used for RS485: Output
7 Not connected
3 TxD+ Signal B (RxD/TxD+): Input/Output 8 TXD- Signal A (RxD/TxD-): Input/Output
4 RTS
2
Request to send (TTL level) Output 9 TXD-
1
Connected for RS422
Not used for RS485: Output
5 GND Logic or communication ground SHELL Chassis ground
1
Pins 2 and 9 are only used as transmit signals for RS422.
2
The RTS is a TTL level signal and can be used to control another half duplex device based on this signal. It is active
when you transmit and is inactive all other times.