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基于C#的PLC串口通信实现

news 2026/5/12 14:09:37

一、基础通信配置

1. 串口参数设置

using System.IO.Ports;public class PlcSerial
{private SerialPort _serialPort;public PlcSerial(string portName, int baudRate = 9600){_serialPort = new SerialPort{PortName = portName,BaudRate = baudRate,Parity = Parity.None,    // 奇偶校验DataBits = 8,            // 数据位StopBits = StopBits.One, // 停止位Handshake = Handshake.None // 流控制};}public void Open() => _serialPort.Open();public void Close() => _serialPort.Close();
}

关键参数说明：

三菱PLC：需设置奇偶校验（如Even）和7位数据位
西门子PLC：常用8数据位+1停止位

二、核心通信协议实现

1. Modbus RTU协议

public class ModbusRTU
{// 生成CRC校验private static ushort CalcCRC(byte[] data){ushort crc = 0xFFFF;foreach (byte b in data){crc ^= (ushort)b;for (int i = 0; i < 8; i++){crc >>= 1;if ((crc & 0x0001) != 0)crc ^= 0xA001;}}return crc;}// 构建Modbus请求帧public static byte[] CreateReadRequest(int slaveId, ushort startAddr, ushort count){byte[] frame = new byte[8];frame[0] = (byte)slaveId;frame[1] = 0x03; // 读保持寄存器frame[2] = (byte)(startAddr >> 8);frame[3] = (byte)startAddr;frame[4] = (byte)(count >> 8);frame[5] = (byte)count;ushort crc = CalcCRC(frame);frame[6] = (byte)crc;frame[7] = (byte)(crc >> 8);return frame;}
}

2. 三菱HostLink协议

public class MitsubishiHostLink
{private const string STX = "\x02";private const string ETX = "\x03";// 构建读指令public static string BuildReadCommand(string address, int length){string cmd = $"{STX}03{address}{length:X2}{ETX}";string fcs = CalcBCC(cmd);return $"{cmd}{fcs}";}// BCC校验算法private static string CalcBCC(string data){byte bcc = 0;foreach (char c in data){bcc ^= (byte)c;}return bcc.ToString("X2").PadLeft(2, '0');}
}

三、数据交互实现

1. 数据读取

public string ReadData(string command)
{try{_serialPort.Write(command);Thread.Sleep(100); // 等待响应if (_serialPort.BytesToRead > 0){string response = _serialPort.ReadExisting();return ParseResponse(response);}}catch (TimeoutException ex){Debug.WriteLine($"读取超时: {ex.Message}");}return null;
}

2. 数据写入

public bool WriteData(string address, object value)
{string command = BuildWriteCommand(address, value);_serialPort.Write(command);// 等待应答string ack = _serialPort.ReadLine();return ack.Contains("\x06"); // 06表示ACK
}

四、关键工程实践

1. 异常处理机制

public void SafeSend(string data)
{try{if (!_serialPort.IsOpen) Open();_serialPort.WriteLine(data);}catch (IOException ex){Reconnect();throw new Exception("通信中断", ex);}
}private void Reconnect()
{Close();Thread.Sleep(1000);Open();
}

2. 多线程数据采集

private void DataPolling()
{while (!_stopFlag){string data = ReadData("ReadRegister");if (!string.IsNullOrEmpty(data)){UpdateUI(ParseData(data));}Thread.Sleep(500); // 采集间隔}
}

五、主流PLC适配方案

PLC品牌	通信协议	地址格式	典型指令示例
三菱	HostLink	D1000→D1000+999	`@00RD000000000100`
西门子	PPI/MPI	%Q0.0,%M100	`05 03 0000 0002 00A0`
欧姆龙	FINS over TCP	W0.0, D100	`46494E53 0000001A ...`
施耐德	Modbus TCP	40001, 40002	`[03][03][00][01][00][01]`

六、调试工具开发

1. 串口调试助手

public class DebugAssistant : Form
{private TextBox _logBox;private SerialPort _debugPort;public DebugAssistant(){_debugPort = new SerialPort("COM2", 9600);_debugPort.DataReceived += (s,e) => _logBox.AppendText(Encoding.ASCII.GetString(e.Buffer));}
}

2. 数据监控看板

public partial class Dashboard : Form
{private Timer _updateTimer = new Timer(1000);public Dashboard(){_updateTimer.Tick += () => UpdatePlcStatus(GetRealTimeData());}
}

参考代码 C# 串口通讯 PLC 实例 www.youwenfan.com/contentcnn/92565.html