Article View: comp.os.msdos.programmer
Article #5670Re: Serial port control?
From: Jerry Gardner
Date: Mon, 08 Apr 1991 22:18
Date: Mon, 08 Apr 1991 22:18
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1492 bytes
In article <1991Apr8.044312.29004@hubcap.clemson.edu> dawill@hubcap.clemson.edu (david williams) writes:
>
> I've just recently aquired my *own* PC, rather than fooling around
>with the computers the school so nicely lets me use. Here's the
>question: How do I set the DTR line inactive after some terminal
>program has finished with the serial port?
To deassert DTR, write a 0 to bit zero of the serial port's Modem Control
register. This register is at I/O port address 0x3fc for COM1 and at
0x2fc for COM2. Writing a zero to the register will deassert all of the
modem control lines. An example in C follows:
outp(0x3fc, 0); /* turn off all modem control lines */
--
Jerry Gardner, NJ6A Altos Computer Systems
UUCP: {sun|pyramid|sco|amdahl|uunet}!altos!jerry 2641 Orchard Parkway
Internet: jerry@altos.com San Jose, CA 95134
Help stamp out vi in our lifetime. (408) 432-6200
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!apple!altos!gumby!jerry From: jerry@gumby.Altos.COM (Jerry Gardner) Newsgroups: comp.os.msdos.programmer,alt.msdos.programmer Subject: Re: Serial port control? Keywords: DTR, reset state? Message-ID: <4790@gumby.Altos.COM> Date: 8 Apr 91 22:18:29 GMT References: <1991Apr8.044312.29004@hubcap.clemson.edu> Reply-To: jerry@altos.COM (Jerry Gardner) Followup-To: comp.os.msdos.programmer Distribution: na Organization: Altos Computer Systems, San Jose, CA Lines: 22