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Serial Communications under XP

Discussion in 'Windows XP' started by tzcreg, Sep 19, 2005.

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  1. tzcreg

    tzcreg Thread Starter

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    Sep 19, 2005
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    We have a DOS serial communication application that has to run under XP. We install our own interrupt handler to handle streaming data from an external device on a standard comm port ie. Comm 1 IRQ 4. The virtual enviroment seams to be working pretty good, allowing us to directly access the IO and IRQ, but it is inconsistent on some machines while working well on others. By monitoring the data and irq requests, some machines seam to give the data in spurts once every second or so... not consistently streaming as is necessary for our application to operate correctly.

    Anyone know if there any fancy register settings to give higher priority to the virtual enviroment or resources. The privledge level adjustments do not have any effect other than filter out keyboard and mouse communications to the app.

    Any documentation for fine tuning the NTVDM or what supporting drivers are associated with it.
    Thanks.
     
  2. DaveBurnett

    DaveBurnett Account Closed

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    Have you tried turning the buffering down on the port off/right down. See device manager serial port advanced .
     
  3. tzcreg

    tzcreg Thread Starter

    Joined:
    Sep 19, 2005
    Messages:
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    Yes, device manager setting had no affect.
    Our application sets up the FIFO buffering to 14 to try and limit the amout of overhead. Its almost as if someother process is also reading the serial port and flushing out the data at the same time... and our application is only getting some of the data, in spurts.
     
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