Siemens PANEL PC 877 operating instructions Serial interface COM 1

Detailed descriptions 17.1 Motherboard

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	–

17-6	SIMATIC Panel PC 877
	Operating instructions, Release 07/2006, A5E00877780-01