$iPkt = “1“;

for ( $i = 1; $i < $pktSize; $i++ )
{
    $iPkt += "1";
}
[download]

You're using numerical addition rather than string concatenation. try the following instead:

    $iPkt .= "1";
[download]

or even better, replace the whole loop with

$iPkt = “1“ x $pktSize;
[download]

Finally, if you want to send data more complex than just a stream of ASCII "1"s, especially binary data, then you may want to check out the pack() function.

Dave.