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Article #2234Re: handshake desired on CPU side of COM port
From: disharp
Date: Sat, 14 Jul 2001 02:46
Date: Sat, 14 Jul 2001 02:46
30 lines
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2239 bytes
On Sat, 14 Jul 2001 01:59:23 GMT, "John Becich" <jbecich@glendale.net> wrote: >I'm reading the COM1 port of my computer with turbo C++ code. I'm using a >simple loop in my code to repeatedly read the COM port and printf the result >to the computer screen. > >The problem is that my program cannot tell the difference between fresh data >on that COM port, and stale data. I get a repeated print out to the screen. > >Isn't there some kind of flag that goes up when new data arrives incoming to >the port from a serial communications line; and down after my computer has >read that data? Might that be DSR, DTR, or similar? > >Thanks, >John > > Hello John, It has been a long time since I was into RS232C protocol. As I remember the transmitting side brings up a line called RTS(REQUEST TO SEND) and the recieving brings up a CTS(Clear to send) line. These signals were used by the modems. As how to implament these signals I will leave to you. Best, Richard
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f5f89,e23dea08d1c53ace X-Google-Attributes: gidf5f89,public X-Google-Thread: 105a80,e23dea08d1c53ace X-Google-Attributes: gid105a80,public X-Google-Thread: f70d1,e23dea08d1c53ace X-Google-Attributes: gidf70d1,public X-Google-Thread: 114af8,e23dea08d1c53ace X-Google-Attributes: gid114af8,public X-Google-ArrivalTime: 2001-07-13 19:46:40 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!newsfeed.google.com!sn-xit-02!supernews.com!news.tele.dk!144.212.100.101!newsfeed.mathworks.com!cyclone.swbell.net!nnrp2.sbc.net.POSTED!not-for-mail From: disharp@swbell.net Newsgroups: alt.comp.hardware,alt.comp.hardware.homebuilt,borland.public.cpp.turbocpp,microsoft.public.win2000.hardware Subject: Re: handshake desired on CPU side of COM port Message-ID: <3b4fb144.36256305@news.swbell.net> References: <%HN37.1912$23.229253@newsread2.prod.itd.earthlink.net> X-Newsreader: Forte Free Agent 1.21/32.243 Lines: 30 Date: Sat, 14 Jul 2001 02:46:28 GMT NNTP-Posting-Host: 209.184.9.213 X-Complaints-To: abuse@swbell.net X-Trace: nnrp2.sbc.net 995078792 209.184.9.213 (Fri, 13 Jul 2001 21:46:32 CDT) NNTP-Posting-Date: Fri, 13 Jul 2001 21:46:32 CDT Organization: SBC Internet Services