Siemens SIMATIC Panel PC 870 Equipment Manual page 102

Hardware Information
Serial port COM1 (PLC/V24/Modem), X30
The serial port (COM 1) on the computer unit is assigned as follows:
Connector
1
13
Gender changer for COM1
You can convert the COM1/V24/PLC port of the SIMATIC PC family into a 25-pin
male connector by means of the enclosed gender changer (25-pin↔25-pin). Plug
the gender changer onto the COM1 socket and secure it with the two Allen screws.
The V24 and TTY interfaces of COM1 can be used alternatively.
7-8
Pin Short
No. Name
1 –
2 TxD (D1)
3 RxD (D2)
4 RTS (S2)
5 CTS (M2)
14
6 DSR (M1)
7 GND (E2)
8 DCD (M5)
9 +TTY RxD
10-17 NC
18 +TTY TxD
19 +20 mA
25
20 DTR (S1)
21 -TTY TxD
22 RI (M3)
23-25 NC
SIMATIC Panel PC 870 Computing Unit, Equipment Manual
Release 11/02
Meaning
Shield
Serial send data
Serial receive data
Request To Send
Clear To Send
Data Set Ready
Station Ground (reference
potential)
Data Carrier Detect
(carrier)
TTY Receive
Not Connected
TTY Send
Isolated power supply
Data Terminal Equipment
Ready
TTY Send
Incoming call
Not Connected
Input /
Output
–
Output
Input
Output
Input
–
Input
Input
–
Output
–
Output Output
Input
–