NetNews Usenet Archive 1992 #30/NN_1992_30.iso/spool/comp/unix/sysv386/17428

Text File | 1992-12-15 | 1.8 KB | 46 lines

Newsgroups: comp.unix.sysv386
From: [e-mail] (Lawrence Kirby)
Path: sparky!uunet!pipex!demon!genesis.demon.co.uk!fred
Subject: Need status of DSR (Carrier Detect) on serial device
Distribution: world
References: <[e-mail]>
Organization: BT
Lines: 33
Date: Wed, 16 Dec 1992 00:29:03 +0000
Message-ID: <[e-mail]>
Sender: [e-mail]


In article <[e-mail]> [e-mail] writes:

>
>We have an Epson serial printer hooked upto an Onboard Systems Stallion
>multiport serial board, and it signals the printer is not ready by
>dropping DTR. As I understand it, this translates into the DSR signal
>(or carrier detect) on the other end. Does anyone know a way through
>the tty interface, or something else, to detect a drop in this signal?
>

This is almost a week old but you don't seem to have a reply (not in this
newsgroup anyway!)

There are 2 possible routes you can take:

1. Use hardware flow control. The printer is essentially using the DTR pin
as a 'ready to receive' signal. I don't Know the Stallion board as such but
you should connect the printer's DTR pin to the flow control input on the
board (usually CTS, sometimes RTS on boards which pretend to be a DCE
device). Make sure the board supports hareware flow control and enable it.

2. Use XON/XOFF flow control. Most printers will support sending XON/XOFF
control codes down the return data line to the computer. Since this is the
only data that goes down this line there are no problems. Just make sure that
both the port and printer are set up for XON/XOFF.

Fred

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Lawrence Kirby | [e-mail]
Wilts, England | [e-mail]
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