How to read RS232 port through PHP

php hardware-interface
Mahendra Jella picture Mahendra Jella · Sep 17, 2013 · Viewed 8.9k times · Source

I'm trying to make a connection using PHP socket libraries but its not working is there any alternate way.

<?php
include "php_serial.class.php";

// Let's start the class
$serial = new phpSerial;

// First we must specify the device. This works on both linux and windows (if
// your linux serial device is /dev/ttyS0 for COM1, etc)
$serial->deviceSet("COM1");

// Then we need to open it
$serial->deviceOpen();

// To write into
$serial->sendMessage("Hello !");

// Or to read from
$read = $serial->readPort();

// If you want to change the configuration, the device must be closed
$serial->deviceClose();

// We can change the baud rate
$serial->confBaudRate(2400);

// etc...
?>

This one is the included file.

php_serial.class.php::

<?php
define ("SERIAL_DEVICE_NOTSET", 0);
define ("SERIAL_DEVICE_SET", 1);
define ("SERIAL_DEVICE_OPENED", 2);

/**
 * Serial port control class
 *
 * THIS PROGRAM COMES WITH ABSOLUTELY NO WARANTIES !
 * USE IT AT YOUR OWN RISKS !
 *
 * @author Rémy Sanchez <[email protected]>
 * @thanks Aurélien Derouineau for finding how to open serial ports with windows
 * @thanks Alec Avedisyan for help and testing with reading
 * @copyright under GPL 2 licence
 */
class phpSerial
{
    var $_device = null;
    var $_windevice = null;
    var $_dHandle = null;
    var $_dState = SERIAL_DEVICE_NOTSET;
    var $_buffer = "";
    var $_os = "";

    /**
     * This var says if buffer should be flushed by sendMessage (true) or manualy (false)
     *
     * @var bool
     */
    var $autoflush = true;

    /**
     * Constructor. Perform some checks about the OS and setserial
     *
     * @return phpSerial
     */
    function phpSerial ()
    {
        setlocale(LC_ALL, "en_US");

        $sysname = php_uname();

        if (substr($sysname, 0, 5) === "Linux")
        {
            $this->_os = "linux";

            if($this->_exec("stty --version") === 0)
            {
                register_shutdown_function(array($this, "deviceClose"));
            }
            else
            {
                trigger_error("No stty availible, unable to run.", E_USER_ERROR);
            }
        }
        elseif(substr($sysname, 0, 7) === "Windows")
        {
            $this->_os = "windows";
            register_shutdown_function(array($this, "deviceClose"));
        }
        else
        {
            trigger_error("Host OS is neither linux nor windows, unable tu run.", E_USER_ERROR);
            exit();
        }
    }

    //
    // OPEN/CLOSE DEVICE SECTION -- {START}
    //

    /**
     * Device set function : used to set the device name/address.
     * -> linux : use the device address, like /dev/ttyS0
     * -> windows : use the COMxx device name, like COM1 (can also be used
     *     with linux)
     *
     * @param string $device the name of the device to be used
     * @return bool
     */
    function deviceSet ($device)
    {
        if ($this->_dState !== SERIAL_DEVICE_OPENED)
        {
            if ($this->_os === "linux")
            {
                if (preg_match("@^COM(\d+):?$@i", $device, $matches))
                {
                    $device = "/dev/ttyS" . ($matches[1] - 1);
                }

                if ($this->_exec("stty -F " . $device) === 0)
                {
                    $this->_device = $device;
                    $this->_dState = SERIAL_DEVICE_SET;
                    return true;
                }
            }
            elseif ($this->_os === "windows")
            {
                if (preg_match("@^COM(\d+):?$@i", $device, $matches) and $this->_exec(exec("mode " . $device)) === 0)
                {
                    $this->_windevice = "COM" . $matches[1];
                    $this->_device = "\\.\com" . $matches[1];
                    $this->_dState = SERIAL_DEVICE_SET;
                    return true;
                }
            }

            trigger_error("Specified serial port is not valid", E_USER_WARNING);
            return false;
        }
        else
        {
            trigger_error("You must close your device before to set an other one", E_USER_WARNING);
            return false;
        }
    }

    /**
     * Opens the device for reading and/or writing.
     *
     * @param string $mode Opening mode : same parameter as fopen()
     * @return bool
     */
    function deviceOpen ($mode = "r+b")
    {
        if ($this->_dState === SERIAL_DEVICE_OPENED)
        {
            trigger_error("The device is already opened", E_USER_NOTICE);
            return true;
        }

        if ($this->_dState === SERIAL_DEVICE_NOTSET)
        {
            trigger_error("The device must be set before to be open", E_USER_WARNING);
            return false;
        }

        if (!preg_match("@^[raw]\+?b?$@", $mode))
        {
            trigger_error("Invalid opening mode : ".$mode.". Use fopen() modes.", E_USER_WARNING);
            return false;
        }

        $this->_dHandle = @fopen($this->_device, $mode);

        if ($this->_dHandle !== false)
        {
            stream_set_blocking($this->_dHandle, 0);
            $this->_dState = SERIAL_DEVICE_OPENED;
            return true;
        }

        $this->_dHandle = null;
        trigger_error("Unable to open the device", E_USER_WARNING);
        return false;
    }

    /**
     * Closes the device
     *
     * @return bool
     */
    function deviceClose ()
    {
        if ($this->_dState !== SERIAL_DEVICE_OPENED)
        {
            return true;
        }

        if (fclose($this->_dHandle))
        {
            $this->_dHandle = null;
            $this->_dState = SERIAL_DEVICE_SET;
            return true;
        }

        trigger_error("Unable to close the device", E_USER_ERROR);
        return false;
    }

    //
    // OPEN/CLOSE DEVICE SECTION -- {STOP}
    //

    //
    // CONFIGURE SECTION -- {START}
    //

    /**
     * Configure the Baud Rate
     * Possible rates : 110, 150, 300, 600, 1200, 2400, 4800, 9600, 38400,
     * 57600 and 115200.
     *
     * @param int $rate the rate to set the port in
     * @return bool
     */
    function confBaudRate ($rate)
    {
        if ($this->_dState !== SERIAL_DEVICE_SET)
        {
            trigger_error("Unable to set the baud rate : the device is either not set or opened", E_USER_WARNING);
            return false;
        }

        $validBauds = array (
            110    => 11,
            150    => 15,
            300    => 30,
            600    => 60,
            1200   => 12,
            2400   => 24,
            4800   => 48,
            9600   => 96,
            19200  => 19,
            38400  => 38400,
            57600  => 57600,
            115200 => 115200
        );

        if (isset($validBauds[$rate]))
        {
            if ($this->_os === "linux")
            {
                $ret = $this->_exec("stty -F " . $this->_device . " " . (int) $rate, $out);
            }
            elseif ($this->_os === "windows")
            {
                $ret = $this->_exec("mode " . $this->_windevice . " BAUD=" . $validBauds[$rate], $out);
            }
            else return false;

            if ($ret !== 0)
            {
                trigger_error ("Unable to set baud rate: " . $out[1], E_USER_WARNING);
                return false;
            }
        }
    }

    /**
     * Configure parity.
     * Modes : odd, even, none
     *
     * @param string $parity one of the modes
     * @return bool
     */
    function confParity ($parity)
    {
        if ($this->_dState !== SERIAL_DEVICE_SET)
        {
            trigger_error("Unable to set parity : the device is either not set or opened", E_USER_WARNING);
            return false;
        }

        $args = array(
            "none" => "-parenb",
            "odd"  => "parenb parodd",
            "even" => "parenb -parodd",
        );

        if (!isset($args[$parity]))
        {
            trigger_error("Parity mode not supported", E_USER_WARNING);
            return false;
        }

        if ($this->_os === "linux")
        {
            $ret = $this->_exec("stty -F " . $this->_device . " " . $args[$parity], $out);
        }
        else
        {
            $ret = $this->_exec("mode " . $this->_windevice . " PARITY=" . $parity{0}, $out);
        }

        if ($ret === 0)
        {
            return true;
        }

        trigger_error("Unable to set parity : " . $out[1], E_USER_WARNING);
        return false;
    }

    /**
     * Sets the length of a character.
     *
     * @param int $int length of a character (5 <= length <= 8)
     * @return bool
     */
    function confCharacterLength ($int)
    {
        if ($this->_dState !== SERIAL_DEVICE_SET)
        {
            trigger_error("Unable to set length of a character : the device is either not set or opened", E_USER_WARNING);
            return false;
        }

        $int = (int) $int;
        if ($int < 5) $int = 5;
        elseif ($int > 8) $int = 8;

        if ($this->_os === "linux")
        {
            $ret = $this->_exec("stty -F " . $this->_device . " cs" . $int, $out);
        }
        else
        {
            $ret = $this->_exec("mode " . $this->_windevice . " DATA=" . $int, $out);
        }

        if ($ret === 0)
        {
            return true;
        }

        trigger_error("Unable to set character length : " .$out[1], E_USER_WARNING);
        return false;
    }

    /**
     * Sets the length of stop bits.
     *
     * @param float $length the length of a stop bit. It must be either 1,
     * 1.5 or 2. 1.5 is not supported under linux and on some computers.
     * @return bool
     */
    function confStopBits ($length)
    {
        if ($this->_dState !== SERIAL_DEVICE_SET)
        {
            trigger_error("Unable to set the length of a stop bit : the device is either not set or opened", E_USER_WARNING);
            return false;
        }

        if ($length != 1 and $length != 2 and $length != 1.5 and !($length == 1.5 and $this->_os === "linux"))
        {
            trigger_error("Specified stop bit length is invalid", E_USER_WARNING);
            return false;
        }

        if ($this->_os === "linux")
        {
            $ret = $this->_exec("stty -F " . $this->_device . " " . (($length == 1) ? "-" : "") . "cstopb", $out);
        }
        else
        {
            $ret = $this->_exec("mode " . $this->_windevice . " STOP=" . $length, $out);
        }

        if ($ret === 0)
        {
            return true;
        }

        trigger_error("Unable to set stop bit length : " . $out[1], E_USER_WARNING);
        return false;
    }

    /**
     * Configures the flow control
     *
     * @param string $mode Set the flow control mode. Availible modes :
     *  -> "none" : no flow control
     *  -> "rts/cts" : use RTS/CTS handshaking
     *  -> "xon/xoff" : use XON/XOFF protocol
     * @return bool
     */
    function confFlowControl ($mode)
    {
        if ($this->_dState !== SERIAL_DEVICE_SET)
        {
            trigger_error("Unable to set flow control mode : the device is either not set or opened", E_USER_WARNING);
            return false;
        }

        $linuxModes = array(
            "none"     => "clocal -crtscts -ixon -ixoff",
            "rts/cts"  => "-clocal crtscts -ixon -ixoff",
            "xon/xoff" => "-clocal -crtscts ixon ixoff"
        );
        $windowsModes = array(
            "none"     => "xon=off octs=off rts=on",
            "rts/cts"  => "xon=off octs=on rts=hs",
            "xon/xoff" => "xon=on octs=off rts=on",
        );

        if ($mode !== "none" and $mode !== "rts/cts" and $mode !== "xon/xoff") {
            trigger_error("Invalid flow control mode specified", E_USER_ERROR);
            return false;
        }

        if ($this->_os === "linux")
            $ret = $this->_exec("stty -F " . $this->_device . " " . $linuxModes[$mode], $out);
        else
            $ret = $this->_exec("mode " . $this->_windevice . " " . $windowsModes[$mode], $out);

        if ($ret === 0) return true;
        else {
            trigger_error("Unable to set flow control : " . $out[1], E_USER_ERROR);
            return false;
        }
    }

    /**
     * Sets a setserial parameter (cf man setserial)
     * NO MORE USEFUL !
     *  -> No longer supported
     *  -> Only use it if you need it
     *
     * @param string $param parameter name
     * @param string $arg parameter value
     * @return bool
     */
    function setSetserialFlag ($param, $arg = "")
    {
        if (!$this->_ckOpened()) return false;

        $return = exec ("setserial " . $this->_device . " " . $param . " " . $arg . " 2>&1");

        if ($return{0} === "I")
        {
            trigger_error("setserial: Invalid flag", E_USER_WARNING);
            return false;
        }
        elseif ($return{0} === "/")
        {
            trigger_error("setserial: Error with device file", E_USER_WARNING);
            return false;
        }
        else
        {
            return true;
        }
    }

    //
    // CONFIGURE SECTION -- {STOP}
    //

    //
    // I/O SECTION -- {START}
    //

    /**
     * Sends a string to the device
     *
     * @param string $str string to be sent to the device
     * @param float $waitForReply time to wait for the reply (in seconds)
     */
    function sendMessage ($str, $waitForReply = 0.1)
    {
        $this->_buffer .= $str;

        if ($this->autoflush === true) $this->flush();

        usleep((int) ($waitForReply * 1000000));
    }

    /**
     * Reads the port until no new datas are availible, then return the content.
     *
     * @pararm int $count number of characters to be read (will stop before
     *  if less characters are in the buffer)
     * @return string
     */
    function readPort ($count = 0)
    {
        if ($this->_dState !== SERIAL_DEVICE_OPENED)
        {
            trigger_error("Device must be opened to read it", E_USER_WARNING);
            return false;
        }

        if ($this->_os === "linux")
        {
            $content = ""; $i = 0;

            if ($count !== 0)
            {
                do {
                    if ($i > $count) $content .= fread($this->_dHandle, ($count - $i));
                    else $content .= fread($this->_dHandle, 128);
                } while (($i += 128) === strlen($content));
            }
            else
            {
                do {
                    $content .= fread($this->_dHandle, 128);
                } while (($i += 128) === strlen($content));
            }

            return $content;
        }
        elseif ($this->_os === "windows")
        {
            /* Do nohting : not implented yet */
        }

        trigger_error("Reading serial port is not implemented for Windows", E_USER_WARNING);
        return false;
    }

    /**
     * Flushes the output buffer
     *
     * @return bool
     */
    function flush ()
    {
        if (!$this->_ckOpened()) return false;

        if (fwrite($this->_dHandle, $this->_buffer) !== false)
        {
            $this->_buffer = "";
            return true;
        }
        else
        {
            $this->_buffer = "";
            trigger_error("Error while sending message", E_USER_WARNING);
            return false;
        }
    }

    //
    // I/O SECTION -- {STOP}
    //

    //
    // INTERNAL TOOLKIT -- {START}
    //

    function _ckOpened()
    {
        if ($this->_dState !== SERIAL_DEVICE_OPENED)
        {
            trigger_error("Device must be opened", E_USER_WARNING);
            return false;
        }

        return true;
    }

    function _ckClosed()
    {
        if ($this->_dState !== SERIAL_DEVICE_CLOSED)
        {
            trigger_error("Device must be closed", E_USER_WARNING);
            return false;
        }

        return true;
    }

    function _exec($cmd, &$out = null)
    {
        $desc = array(
            1 => array("pipe", "w"),
            2 => array("pipe", "w")
        );

        $proc = proc_open($cmd, $desc, $pipes);

        $ret = stream_get_contents($pipes[1]);
        $err = stream_get_contents($pipes[2]);

        fclose($pipes[1]);
        fclose($pipes[2]);

        $retVal = proc_close($proc);

        if (func_num_args() == 2) $out = array($ret, $err);
        return $retVal;
    }

    //
    // INTERNAL TOOLKIT -- {STOP}
    //
}
?>

I am using this way but its not working fine.

Answer

KGolding picture KGolding · Oct 3, 2013

If you are running this on Windows as your choice of 'COM1' leads me to believe, then there is a known issue when with the port never timing out. I have successfully over come this using a batch file to start my php script, but calling comconfig.exe first to fix the issue:

REM Fix bug with Windows serial port timeout not working
comconfig.exe COM1
php.exe myscript.php

I also run the MODE command when my script starts using the following line, but am I not sure this is required (belts and braces though!):

exec('MODE COM1 to=on');

I had a lot of trouble finding the comconfig.exe program, so I've uploaded it complete with the required vcredist.exe for you:

https://dl.dropboxusercontent.com/u/2770237/comconfig.zip

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