Siemens SIMATIC PANEL PC 877 - Page 198

Detailed descriptions
17.1 Motherboard
SIMATIC Panel PC 877
17-6 Operating instructions, Release 07/2006, A5E00877780-01
Serial interface COM 1, X30
The serial interface (COM 1) on the device has the following pinout:
Serial interface COM 1 (socket)
PinNo. Abbreviation Meaning Input/Output
1 – Shielding –
2 TxD (D1) Serial transmit data Output
3 RxD (D2) Serial receive data Input
4 RTS (S2) Request to send Output
5 CTS (M2) Clear to send Input
6 DSR (M1) Ready for operation Input
7 GND (E2) System ground (reference
potential)
–
8 DCD (M5) Data carrier detect Input
9 – – –
10–17 – Not assigned –
18 – – –
19 – – –
20 DTR (S1) Data terminal ready Output
21 – – –
22 RI (M3) Incoming call Input
23–25 – Not assigned –