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From: j@uriah.heep.sax.de (J Wunsch)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Setting up Dumb Terminal
Date: 2 Sep 1996 07:33:48 GMT
Organization: Private BSD site, Dresden
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chiuc@po.EECS.Berkeley.EDU (Chun-Yang Chiu) wrote:

> tip to talk to the dumb terminal.  A previous post indicated that
> getty sleeps on DCD, and I think that could be my problem.  However,
> I dont know how to check whether my null modem cable carries the DCD
> signal or not, and if it does, how to enable DCD in telix/telemate.
> (The telix status bar always says "Offline"..is that related?)

It's certainly related. :-)

A proper null-modem cable looks like:

	TxD	2 ---\ /--- 2   TxD
		      X
	RxD	3 ---/ \--- 3   RxD

	RTS	4 ---\ /--- 4   RTS
		      X
	CTS	5 ---/ \--- 5   CTS

	DSR	6 -+     +- 6   DSR
		   |	 |
	GND	7 -|-----|- 7   GND
		   |	 |
	DCD	8 -*-\ /-*- 8   DCD
		      X
	DTR    20 ---/ \--- 20  DTR


The 20 <-> 6+8 crossover will generate DCD and DSR from the remote
DTR, thus the pseudo-carrier will appear as soon as the modem
indicates `ready'.  Since the open tty port on the Unix side will also
raise DTR, your Telix should get "online" seeing its own DCD signal.

--
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)