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From: msmith%peruvian.utah.edu@cs.utah.edu (Matthew Smith)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Need help setting DTR or RTS high or low
Message-ID: <1991Jun21.130204.6197@hellgate.utah.edu>
Date: 21 Jun 91 19:02:04 GMT
References: <0094A6B3.5314B580@MAPLE.CIRCA.UFL.EDU>
Organization: University of Utah CS Dept
Lines: 24

In article <0094A6B3.5314B580@MAPLE.CIRCA.UFL.EDU> sorrow@oak.circa.ufl.edu writes:
>I need some code examples on how to set the DTR or RTS line on a 
>RS-232C port high or low.  C or asm would be fine.
>
>Thanks,
>
>Brian
>/*
>Brian Hook -- MS-DOS Programmer for Contract

The Modem Control Register (address base address+0x04) is a bit mask of the
various control lines, DTR, RTS, CTS, etc... 

To turn on RTS, turn on bit 1 (of bits 0-7 0=LSB), and to turn it off, set
it to 0.

DTR is controlled by bit 0 in the same register.

I hope this helps you out.  I figured it would be better than code...

Matt Smith
msmith@peruvian.utah.edu
University of Utah
Department of Computer Science