connect_modbus.php

   <?php
   require_once 'vendor/autoload.php';

   use PhpModbus\PhpType;
   use PhpModbus\ModbusMaster;

   function connect_modbus($ip, $port) {
       $modbus = new ModbusMaster($ip, "TCP");
       $modbus->port = $port;
       $modbus->connect();
       return $modbus;
   }
   ?>