Siemens S5-155U System Manual page 503

Connector Assignments
10 - 16
Assignments of the CPU front connector (PG interface)
Pin No. Designation
1 Housing/0 V/0 V
2 R x D
3 VPG + 5 V DC
4 + 24 V from bus
5 0 V/0 V
int
6 TxD
7 TxD
8 Housing/0 V/0 V
9 R x D
10 24 V ground
11 20 mA/transmitter
12 0 V/0 V
int
13 20 mA/receiver
14 VPG + 5 V DC
15 0 V/0 V
int
ext
ext
System Manual
C79000-T8576-C199-03