Serial Ports

This is a discussion on Serial Ports within the C Programming forums, part of the General Programming Boards category; Hi, everybody, Does anyone know how to read data from a serial port (RS232)? A tried to use open and ...

  1. #1
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    Exclamation Serial Ports

    Hi, everybody,

    Does anyone know how to read data from a serial port (RS232)?
    A tried to use open and read commands.
    It seems that the open command worked well, but the read command always returns -1.
    This is how I used them:
    fd=open("/dev/ttyS0",O_RDWR | O_NOCTTY | O_NONBLOCK);

    result=read(fd,mybuffer,mysize);

    I'm trying to test this with a serial barcode scanner.

    If there is anyone who can help me, I'd be very grateful.

    Thanks,

    Vanessa

  2. #2
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    It depends what type of operating system environment that your program is running on.

    If you are using windows then look for microsoft doc on the WIN32 comm API. A better method would be to buy a 3rd party communication package that know the intricies of the comm API such as the Sysfire/Greenleaf comm libraries.

    I'm sorry that I can't supply you with info on serial comms on other operating systems.


    Bob

  3. #3
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    > O_NONBLOCK);
    Well unless you have already scanned something, your read call will return immediately, whether there is any data or not.

    Either remove the NON_BLOCK and let read just wait until there's something on the port, or surround the read with a loop to continually monitor for possible input.

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