3Com CS/2500 manual Txd

A-2 APPENDIX A: PIN ASSIGNMENTS

The table also lists pins assigned for RS-422 functions, when the port is configured for RS-422 in the firmware. You can use the table as a reference for cables supplied by 3Com.

CAUTION: A chassis ground connection between the communications server and customer equipment is strongly recommended. This connection minimizes the potential for equipment damage caused by electrostatic discharges. On models CS/2500 and CS/2600, the chassis ground connection on serial ports can be made only through the connector headshells. Do not use pin 1 for this connection, since it is not connected to the chassis.

Table A-1 RS-232 Serial Port Pin Assignments

	RS-232-	3Com		Failsafe
Pin	D Name	Name	Direction	State	Function
1	—	—	—	—	Not used
2	BA	TXD	In	Break	Transmit Data
3	BB	RXD	Out	—	Receive Data
4	CA	RTS	In	True	Request to Send
5	CB	CTS	Out	—	Clear to Send
6	CC	DSR	Out	—	Data Set Ready
7	AB	GND	—	—	Signal Ground
8	CF	DCD	Out		Received Line Signal
					Detector (Data Carrier
					Detect)
9–10	—	—	—	—	Not used
11*	DTE	DCE	In	—	DCE Data Set Ready
	DSR	DSR
12	—	—	—	—	Not used
13	—	TXD-B	In	Break	RS-422 Transmit Data
14	—	TXD-A	In	Break	RS-422 Transmit Data
15	DB	TXC	Out	—	Transmit Clock
16	—	RXD-A	Out	—	RS-422 Receive Data
17	DD	RXC	Out	—	Receive Clock
18	—	—	—	—	Not used
19	—	RXD-B	Out	—	RS-422 Receive Data
20	CD	DTR	In	False	Data Terminal Ready