How to use PHP to parse and display Modbus TCP data reports

How to use PHP to parse and display Modbus TCP data reports

In industrial control systems, Modbus TCP is a commonly used communication protocol for data exchange between devices. When developing applications, parsing and displaying Modbus TCP data reports is a very important task. This article will introduce how to use the PHP programming language to parse and display Modbus TCP data reports, with code examples.

1. Preparation
Before starting, we need to ensure that PHP has been installed and has a basic development environment. At the same time, the IP address and port number of the Modbus TCP server need to be provided to the script as parameters.

2. Connect and read data
First, we need to use PHP's socket function to establish a connection with the Modbus TCP server and send a request to read data. The following is a simple sample code:

<?php
// Modbus TCP服务器的IP地址和端口号
$server_ip = '192.168.1.100';
$server_port = 502;

// 创建一个socket连接
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
    die("无法创建socket连接: " . socket_strerror(socket_last_error()) . "
");
}

// 连接到Modbus TCP服务器
$result = socket_connect($socket, $server_ip, $server_port);
if ($result === false) {
    die("无法连接到Modbus TCP服务器: " . socket_strerror(socket_last_error($socket)) . "
");
}

// 向服务器发送读取数据的请求

$result = socket_write($socket, $request, strlen($request));
if ($result === false) {
    die("无法发送请求到Modbus TCP服务器: " . socket_strerror(socket_last_error($socket)) . "
");
}

// 读取服务器返回的数据
$response = socket_read($socket, 1024);
if ($response === false) {
    die("无法从Modbus TCP服务器读取数据: " . socket_strerror(socket_last_error($socket)) . "
");
}

// 关闭socket连接
socket_close($socket);

// 解析并展示数据
$data = unpack('C*', $response);
foreach ($data as $value) {
    echo $value . ' ';
}
?>

The above code uses PHP's socket-related functions to connect and read data from the Modbus TCP server. It should be noted that request and response data are sent and received in binary format, so the unpack function needs to be used to parse and obtain specific values.

3. Parse and display data
After obtaining the data returned by the Modbus TCP server, we need to parse it and display it to the user in a specific format. The following is a simple sample code:

<?php
// 假设Modbus TCP服务器返回的数据为：
$data = array(1, 0, 2, 0, 3, 0, 4, 0, 5, 0);

// 解析并展示数据
for ($i = 0; $i < count($data) - 1; $i += 2) {
    $value = ($data[$i] << 8) + $data[$i+1];
    echo "寄存器 " . ($i / 2 + 1) . ": " . $value . "
";
}
?>

The above code converts the received data into an unsigned 16-bit integer and displays it in register order.

4. Complete program example
Combining the connection and parsing codes, we can write a complete program to parse and display Modbus TCP data reports. The following is a simple example:

<?php
// Modbus TCP服务器的IP地址和端口号
$server_ip = '192.168.1.100';
$server_port = 502;

// 创建一个socket连接
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
    die("无法创建socket连接: " . socket_strerror(socket_last_error()) . "
");
}

// 连接到Modbus TCP服务器
$result = socket_connect($socket, $server_ip, $server_port);
if ($result === false) {
    die("无法连接到Modbus TCP服务器: " . socket_strerror(socket_last_error($socket)) . "
");
}

// 向服务器发送读取数据的请求

$result = socket_write($socket, $request, strlen($request));
if ($result === false) {
    die("无法发送请求到Modbus TCP服务器: " . socket_strerror(socket_last_error($socket)) . "
");
}

// 读取服务器返回的数据
$response = socket_read($socket, 1024);
if ($response === false) {
    die("无法从Modbus TCP服务器读取数据: " . socket_strerror(socket_last_error($socket)) . "
");
}

// 关闭socket连接
socket_close($socket);

// 解析并展示数据
$data = unpack('C*', $response);
for ($i = 0; $i < count($data) - 1; $i += 2) {
    $value = ($data[$i] << 8) + $data[$i+1];
    echo "寄存器 " . ($i / 2 + 1) . ": " . $value . "
";
}
?>

With the above code, we can connect to the Modbus TCP server and read and display the data reports therein.

Summary
Using PHP to parse and display Modbus TCP data reports requires three steps: connecting, reading data and parsing. This article provides a simple sample code that I hope will be helpful to readers. In actual applications, more processing and adjustments may be required depending on specific requirements and data formats.

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