VarAC on Linux/Pi/Mac

I am attempting to read the QRG of my ICOM7610 by means of a simple PHP program by having connect the RIG to the USB port. I

am using OSX.

Different logging system I am using on such an host are working well.

When I attempt to send the string \xFE\xFE\x98\xE0\x03\xFD nothing coming back.

Here the very trivial program of example

<?php

$fp=fopen("/dev/cu.SLAB_USBtoUART4","wb+");

if($fp==null){echo "nooo\n"; exit(0);}

fwrite($fp,"\xFE\xFE\x98\xE0\x03\xFD",6);

$line=fread($fp,6);

for($i=0;$i<5;$i++){

echo dechex(ord($line[$i]));

echo " ";

}

echo "\n";

?>

Any help?

73 de IK4LZH John