Hi. Thank you for your replys. I think I can be now more specific about my issue of the buffer overflow error. The routine I call for COM5 serial handshaking is Serial_TrxRcv( $commandForTransmission ). In my main routine I have a sub doing this which is below; 

sub ProcessPIDs {
    
    # print "Inside ProcessPIDs \n";

    # Process the input arguments
    my ( $nickname, $ref_nicknametocommand ) = @_;
    my %InSubNickNameToCommand = %{$ref_nicknametocommand};   # De-ref
+erence the reference to a hash
        my $ccmd;
    
        $ccmd = $InSubNickNameToCommand{ $nickname };             # ne
+ed further ERROR checking here  !!!!!!
    
    
        my $newcmd = '0101';
        print "\$ccmd; $ccmd ".length($ccmd). " \$newcmd; $newcmd ".le
+ngth($newcmd)."\n";
        # my $newcmd = $ccmd;    # not work
    my $response = Serial_TrxRcv($newcmd);
    my $result;

     ...etc...

[download]

If I use Serial_TrxRcv in the manner as above, I do not have error. If I call the same but with the parameter $ccmd then I get the error. This $ccmd is initialised from a hash structure. The hash is to provide quick mapping from a nickname to the wanted command string. I provide a comparison between these 2 parameters with the just above programs and the console output below; 


TPA 
$ccmd; 0101 4 $newcmd; 0101 4
cmd; 0101 x x
MonStatus      Cmd; 0101 Length; 21  Response; 41 01 00 07 61 00 __>.
$nickname MonStatus; 00 07 61 00
TPB

[download]

The non-faulty and faulty parameters both appear the same and have the same lengths. So, do people have any further ideas about my problem ??

Thanks. Regards JC.....

In reply to Re^3: Win32::SerialPort, buffer overflow by jmClifford
in thread Win32::SerialPort, buffer overflow by jmClifford

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.