Western Telematic CAS-81 manual Description of System Interfaces, Control Port DB25 Female

A. Description of System Interfaces

A.1. Control Port (DB25 Female)

The Control Port is a 25 pin female connector wired in a DCE (modem) configuration.

			Not
Pin	Signal	I/O	Connected	Connected
2	RXD	Input	-	To Serial Port Pin 3
3	TXD	Output	Low	Follows Serial Port
4	RTS	Input	-	To Serial Port Pin 7
5	CTS	Output	High	* Follows Serial Port
6	DSR	Output	High	Always High
7	GND	Signal Ground
8	DCD	Output	Low	* Follows Serial Port
20	DTR	Input	-	To Serial Port Pin 4

*May be forced high by DIP Switches 9 and 10. Always high when all Serial Ports are connected.

Figure A. 1: Control Port / Serial Port Interface

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