Hexnr. through serial COM port

This is a discussion on Hexnr. through serial COM port within the C++ Programming forums, part of the General Programming Boards category; Hi, IŽd like to send hexnumbers through the serial interface of a PC to a ” processor. It works with ...

  1. #1
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    Hexnr. through serial COM port

    Hi,
    IŽd like to send hexnumbers through the serial interface of a PC to a ” processor.
    It works with a terminal, when I hit a key, for example 'a', 0100001 is stored in the ”p register.
    This I`d like to accomplish with the following C++ routine:

    while(i<rows &&fgets(buff, sizeof(buff), HexCode) != NULL
    {
    for ( j=0; j<=1; j++ )
    {
    if (sscanf(&buff[0],"%c%c",&x[i][j])==1)
    i++ ;

    ( Im intending to grab the first two chars of a textfile, resembling the byte in Hex format, like:
    FD
    9A
    DF.......


    The send routine through Com1 looks like this:

    WriteFile(hCom, &x[][], sizeof (x[][] ), &dwWritten, NULL);


    The PC crashes upon compilation, though.

    Im I doing the right thing to achiev what I want?
    I`d appreciate any help.

  2. #2
    and the hat of wrongness Salem's Avatar
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    So are you trying to send say FD as one byte - 0xFD or as two bytes of a string "FD"

    And what's with all the x[][] ?

    PS
    Don't forget the code tags
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  3. #3
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    I`m not shure.I think it should be sent as one byte, sunce that`s what the ”p processes at he other end.
    Is that what happens when I hit a key of the keyboard?

    the [][] contain the indexes of the for loops.

    Do hou have any idea how to send this data as one byte?

  4. #4
    and the hat of wrongness Salem's Avatar
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    I guess something like this
    Code:
        char buff[] = "FCDA\n"; // example buffer from fgets
        int x;
        unsigned char c;
        sscanf(buff,"%02x",&x); // take only the first 2 chars
        printf("%x\n",x);
        c=x;                    // make it a single char
        WriteFile(hCom, &c, 1, &dwWritten, NULL);
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

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