OPC在自动化行业使用很广泛，好一点的PLC支持OPC协议，比如国内的汇川、禾川PLC对应高端的PLC都支持OPC UA协议，低端一点的则使用Modbus和上位机通讯，或者TCP自定义格式。相比于modbus协议，OPC不用确定寄存器地址，可以主动查询到OPC服务端对应的所有变量及属性，以object为根节点。

        OPC在C#中开发使用客户端方法很多，可以自行搜索，如果OpcUaHelper等。作为服务端，可以使用github上OPC开源代码，也可以使用如下介绍的opc.uafx.advanced（使用简单）。

        更多OPC介绍，参考我之前我的内容。

参考网站：OPC UA SDK for .NET - Client / Server in C# VB.NET schnell und einfach

NuGet添加引用：opc.uafx.advanced

服务端示例代码：https://docs.traeger.en/de/software/sdk/opc-ua/net/server.development.guide

客户端示例代码：Client Development Guide & Tutorial - TRAEGER Docs

客户端

using System;
using System.Threading;using Opc.UaFx.Client;public class Program 
{public static void Main(){using (var client = new OpcClient("opc.tcp://localhost:4840")) {client.Connect();while (true) {var temperature = client.ReadNode("ns=2;s=Temperature");Console.WriteLine("Current Temperature is {0} °C", temperature);Thread.Sleep(1000);}}}
}

服务端

using System.Threading;using Opc.UaFx;
using Opc.UaFx.Server;class Program
{public static void Main(){var node = new OpcDataVariableNode<double>("Temperature", 100.0);using (var server = new OpcServer("opc.tcp://localhost:4840/", node)) {      server.Start();while (true) {if (node.Value == 110)node.Value = 100;elsenode.Value++;node.ApplyChanges(server.SystemContext);Thread.Sleep(1000);}}}
}

打开服务端和客户端的示例代码

using Opc.UaFx;
using Opc.UaFx.Client;
using Opc.UaFx.Server;// Define the root node of server
var machineNode = new OpcObjectNode("Machine");
// Declear a variable Hello world like very started.
var messageNode = new OpcDataVariableNode<string>("Message", "Hello World!");// It's a variable set to false.
bool variableValue = false;// bind the variable to root.
var isRunningNode = new OpcDataVariableNode<bool>(machineNode,"IsRunning",value: variableValue);// bind another one in case.
var jobNode = new OpcObjectNode(machineNode,"Job",new OpcDataVariableNode<bool>("Cancel", false),new OpcDataVariableNode<int>("State", -1));// New a opc server. Make sure tcp port 4840 haven't been used before
using var server = new OpcServer("opc.tcp://localhost:4840/", machineNode, messageNode);// Start it
server.Start();// Wait a second
Thread.Sleep(1000);
//while (true) ;// New a client to connect to 4840
using var client = new OpcClient("opc.tcp://localhost:4840/");// Connect anyway
client.Connect();// Print the variable value. It should be false here.
Console.WriteLine(client.ReadNode("ns=2;s=Machine/IsRunning"));// Write some values.
OpcStatusCollection results = client.WriteNodes(new OpcWriteNode("ns=2;s=Machine/Job/Cancel", true),new OpcWriteNode("ns=2;s=Machine/Job/State", 0));
// Print them.
Console.WriteLine(client.ReadNode("ns=2;s=Machine/Job/Cancel"));
Console.WriteLine(client.ReadNode("ns=2;s=Machine/Job/State"));