3Com 3C16987A manual Modem Cable, RJ45 Pin, Assignments, Pin Number, Signal, Function

42APPENDIX B: PIN-OUTS

Modem Cable	9-pin to RS-232 25-pin
	Switch 3300 SM		RS-232 Modem Port
	Cable connector: 9-pin female		Cable connector: 25-pin male
	Screen	Shell	1	Screen
	TxD	3	2	TxD
	RxD	2	3	RxD
	RTS	7	4	RTS
	CTS	8	5	CTS
	DSR	6	6	DSR
	Ground	5	7	Ground
	DCD	1	8	DCD
	DTR	4	20	DTR

RJ45 Pin	Pin assignments are identical for 10BASE-T and 100BASE-TX RJ45
Assignments	connectors
	Table 7 Pin assignments

Pin Number	Signal	Function
Ports configured as MDI
1	TxData +	Transmit data
2	TxData –	Transmit data
3	RxData +	Receive Data
4	Not assigned
5	Not assigned
6	RxData –	Receive data
7	Not assigned
8	Not assigned