Thread: Serial Communication Timeout Problem

  1. #1
    Registered User
    Join Date
    Jan 2003

    Serial Communication Timeout Problem

    Trying to receive data from a device, via the coms port.

    This all works fine whilst using an overlapped structure, and a very large timeout (FFFFFFFF). When this is reduced, or the overlapped replaced by a non-overlaped, then the entire system seizes up, and the only response is to switch off pc (cold boot).

    This all seems to go wrong on the ReadFile (Visual C++ 6) command.

    Grateful for any hints, as my head has started to hurt, and the plaster on the walls is starting to crumble!!!!!!!!!


  2. #2
    Hardware Engineer
    Join Date
    Sep 2001

    I guess nobody has your answer...

    There is lots of info about programming the ports at

    The only port programming I've done was in DOS BASIC (a long-long time ago).

    I suspect your problem is related to your Multitasking OS (Windows?) doing stuff in the background to mess-up your timing and maybe delaying access to the port. It could be an interrupt related problem too. Although, I don't remember being required to use interrupts at all with my particular DOS BASIC application... I don't think there was anything related to IRQs in my program.

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