Siemens SIMATIC PC 670 Equipment Manual page 144

Hardware Information
Serial interface COM2 (V24/Mouse)
The serial interface (COM2) of the computing unit is assigned as follows
Figure 7-2
Pin No. Short Name
1 DCD (M5)
2 RxD (D2)
3 TxD (D1)
4 DTR (S1)
5 GND (E2)
6 DSR (M1)
7 RTS (S2)
8 CTS (M2)
9 RI (M3)
7-12
5
9
6
1
Serial interface COM2 (male)
Meaning
Data carrier detect
Received data
Transmission data
Data terminal equipment
ready
Station ground
Data set ready
Request to send
Clear to send
Incoming call
Input/Output
Input
Input
Output
Output
-
Input
Output
Input
Input
Panel PC 670 Computing Unit, Equipment Manual
Release 04/02