Siemens S7-1200 System Manual page 977

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