Windows – Communicating serial port on windows with php


I'm working with an application which connects to Huawei 3G Modem using COM ports in php. Here is my code:

$sms = new sms();
$device = "COM11";
exec("mode $device BAUD=9600 PARITY=n DATA=8 STOP=1 xon=off octs=off rts=on");
$comport = fopen($device, "r+b");
if ($comport === false){
    die("Failed opening com port<br/>");
    echo "Com Port Open<br/>";

//Set non-blocking mode for writing
//stream_set_blocking($comport, 0);
$atcmd = "AT\r";
fputs($comport, $atcmd);

sleep(5); // Sleep for response from the modem

 // Set blocking mode for reading
$res = fgets($comport, 4017);
if(trim($res) == "OK"){
    echo "Modem supports AT Commands<br/>";
    echo "Error response: ".$res;



    class sms{
        function _blocking($device,$mode){
            stream_set_blocking($device, $mode);
            return true;

This is working fine with me. Now challenge is every time i connect to the new usb port the COM was changing for my modem. Is there any other way to detect the device automatically with php in windows ?

Best Solution

You need to determinate COM port number of your USB device via some external command called trough PHP's shell_exec().

For Windows you can try this small tool:

After you call this tool via shell_exec(), you need to parse it's output (RegExp) and look for exact COM port number based on company/device name.