<?php

	// declare variables
	$handle 	= $reply = null;
	$filename	= '/dev/ttyUSB1';
	$handle	= @fopen($filename, 'r+');

	// validate file handle
	if ( !is_file($handle) ){
		echo 'The device isn\'t detected';

	}else{ // main code.

		if ( fwrite($handle, 'AT') ) {
			echo 'Command is sent';
			$reply = fread($filename, 4);
			echo $reply;
			exit;

		}else{
			echo 'The device isn\'t read';
		}

		fclose( $handle );
	}

	die;

?>