hello guys, i'm using system() command in php to execute command in terminal through php but it seems like there's a problem occured. Below is the simple code in php

PHP Code:
<?php
$command 
system('perl -e' print "\xF5\x01\x00\x01\x03\x00\x03\xF5"'>/dev/ttyUSB0 ');
?>
it suppose send command to the serial port and light up my LED but it seems like nothing happened. Please share your idea guys. Thank you.