Article View: comp.os.msdos.programmer
Article #5673Re: Serial port control?
From: Adam Goldberg
Date: Tue, 09 Apr 1991 02:44
Date: Tue, 09 Apr 1991 02:44
28 lines
2076 bytes
2076 bytes
In article <4790@gumby.Altos.COM>, jerry@gumby.Altos.COM (Jerry Gardner) writes:
>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 */
Not really a good idea, they might not all get reset to the proper value the
next time you go to use it. A better idea would be:
outportb(0x3fc,(inportb(0x3fc) & 0xfe)); /* set bit 0 to 0 */
+----------------------------------------------------------------------------+
+ Adam Goldberg Bitnet: tabu6@ISUVAX.BITNET +
+ Iowa State University Internet: tabu6@CCVAX.IASTATE.EDU +
+ "It's simple! Even a Pascal programmer could do it!" +
+ "Remember: The sooner you fall behind, the more time you have to catch up" +
+----------------------------------------------------------------------------+
Technical Details
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<1991Apr8.044312.29004@hubcap.clemson.edu>,<4790@gumby.Altos.COM>Show Full Headers
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!sdd.hp.com!news.cs.indiana.edu!ux1.cso.uiuc.edu!news.iastate.edu!VAXF.IASTATE.EDU!TABU6 From: tabu6@CCVAX.IASTATE.EDU (Adam Goldberg) Newsgroups: comp.os.msdos.programmer Subject: Re: Serial port control? Message-ID: <1991Apr9.024404.9824@news.iastate.edu> Date: 9 Apr 91 02:44:04 GMT References: <1991Apr8.044312.29004@hubcap.clemson.edu>,<4790@gumby.Altos.COM> Sender: news@news.iastate.edu (USENET News System) Reply-To: tabu6@CCVAX.IASTATE.EDU Distribution: na Organization: Iowa State University, Ames, IA. Lines: 29