Implementation of the basic functionality of the Modbus TCP and UDP based protocol using PHP. This is the Google code project follower at https://code.google.com/p/phpmodbus/

Implemented features:

• Modbus master
• FC1 - Read coils
• FC2 - Read input discretes
• FC3 - Read holding registers
• FC4 - Read holding input registers
• FC5 - Write single coil
• FC6 - Write single register
• FC15 - Write multiple coils
• FC16 - Write multiple registers
• FC23 - Read/Write multiple registers

Example:

require_once dirname(__FILE__) . '/Phpmodbus/ModbusMaster.php'; 

// Modbus master UDP
$modbus = new ModbusMaster("192.168.1.1", "UDP"); 
// Read multiple registers
try {
    $recData = $modbus->readMultipleRegisters(0, 12288, 5); 
}
catch (Exception $e) {
    // Print error information if any
    echo $modbus;
    echo $e;
    exit;
}
// Print data in string format
echo PhpType::bytes2string($recData); 

For more see [https://code.google.com/p/phpmodbus/downloads/list documentation] or [https://code.google.com/p/phpmodbus/wiki/FAQ FAQ].

Note:

• The PHP extension php_sockets.dll should be enabled (server php.ini file)