Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!killer!pollux!dalsqnt!usl!usl-pc!jpd
From: jpd@usl-pc.usl.edu (DugalJP)
Newsgroups: comp.dcom.modems
Subject: Re: Break definition
Message-ID: <33@usl-pc.usl.edu>
Date: 8 Sep 88 14:55:24 GMT
References: <402@ucrmath.UUCP>
Reply-To: jpd@usl-pc.UUCP (DugalJP)
Organization: Univ. of Southwestern La., Lafayette
Lines: 26

In article <402@ucrmath.UUCP> jantypas@ucrmath.UUCP (John Antypas) writes:
>I purchased a California Communications Corp. 2400 baud internal modem.
>Overall, it works just fine under Unix, but I have yet to be able to
>send a "break tone".  The problem appears to be that CCC didn't know how
>to handle a break.  They claim the modem has a litteral serial port
>on it so there should be no problems but...
>
>CCC is willing to correct the problem but they need to know how to handle
>the break.  After all, there is no such thing as a break character.  What

A break can be detected by many UARTS as a NULL received with a framing
error.  Think of a break as a start bit that persists for much longer that
a character time, perhaps 250 ms.  Many uarts can be programmed to send a
break with a special order, but if not, changing to the slowest baud and
sending a null might work.  This of course is a real kludge and has nasty
side effects if the uart can't support different send and receive bauds.

Good luck getting your modem fixed ... I'm doubtful they'll fix it.

You may be able to add a break switch to your modem by modifying the
input to the RS232 line driver chip.

-- 
-- James Dugal,	N5KNX		USENET: ...!{dalsqnt,killer}!usl!jpd
Associate Director		Internet: jpd@usl.edu
Computing Center		US Mail: PO Box 42770  Lafayette, LA  70504
University of Southwestern LA.	Tel. 318-231-6417	U.S.A.