How to implement Modbus TCP remote access through PHP

How to implement Modbus TCP remote access through PHP

Modbus is a communication protocol used to exchange data between controllers and devices in the field of industrial automation. Modbus TCP is a Modbus protocol based on TCP/IP communication on Ethernet. Using PHP language, we can easily implement remote access to Modbus TCP. This article will introduce how to implement Modbus TCP remote access through PHP and provide sample code.

Step 1: Install the PHP Modbus library
First, we need to install the PHP Modbus library in the PHP environment. It can be installed through Composer, open a terminal and switch to the project directory, run the following command:

composer require php-modbus/php-modbus

Step 2: Create a Modbus TCP connection
In In PHP code, we can establish a connection with Modbus TCP devices by using the PHP Modbus library. The following is a sample code:

<?php

require 'vendor/autoload.php';

use PhpModbusPhpModbus;

$ip = '192.168.0.10';    // Modbus TCP设备的IP地址
$port = 502;             // Modbus TCP设备的端口号

$phpModbus = new PhpModbus();
$phpModbus->connectTCP($ip, $port);

// 连接成功后，可以进行数据的读写操作

// 关闭连接
$phpModbus->disconnect();

?>

Step 3: Read Modbus register data
After establishing the Modbus TCP connection, we can use the PHP Modbus library to read the register data on the Modbus device. The following is a sample code:

<?php

// 建立Modbus TCP连接，参考步骤2

$startAddress = 0;        // 起始寄存器地址
$quantity = 10;           // 读取寄存器的数量

// 读取指定数量的寄存器数据
$readData = $phpModbus->readMultipleRegisters(0, $startAddress, $quantity);

// 打印读取到的寄存器数据
print_r($readData);  

?>

Step 4: Write Modbus register data
In addition to reading register data, we can also use the PHP Modbus library to write register data on the Modbus device. The following is a sample code:

<?php

// 建立Modbus TCP连接，参考步骤2

$registerAddress = 0;     // 写入寄存器的地址
$data = [100, 200, 300];  // 需要写入的数据

// 写入寄存器数据
$phpModbus->writeMultipleRegisters(0, $registerAddress, $data);

?>

In summary, by using the PHP Modbus library, we can easily achieve remote access to Modbus TCP. After the connection is established, data interaction with Modbus devices can be performed by reading and writing register data. I hope this article can help you successfully implement Modbus TCP remote access in your PHP project.

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