Siemens Simatic Field PG Manual page 98

Hardware Information
COM1 (V.24/TTY)
Serial interface COM1 (AG/V.24/Modem). Pinout:
Pin No. Designation
1 -
2 TxD (D1)
3 RxD (D2)
4 RTS (S2)
5 CTS (M2)
6 DSR (M1)
7 GND (E2)
8 DCD (M5)
9 +TTY RxD
10 - 17 -
18 +TTY TxD
19 +20mA
20 DTR (S1)
21 -TTY TxD
22 RI (M3)
23-25 -
7-8
1
14
25
13
Description
Shield
Serial transmit data
Serial receive data
Request to send
Clear to send
Data set ready
Functional ground
(reference potential)
Data carrier detect
TTY receive
Unassigned
TTY send
Isolated current source
Data terminal ready
TTY send
Incoming call
Unassigned
Input /Output
-
Output
Input
Output
Input
Input
-
Input
Input
-
Output
-
Output
Output
Input
-
SIMATIC Field PG Manual
A5E00075760-04