此时会有如下报错，因为 opc库文件 没有导入，第二步就是去导入各种依赖。
Assembly 'Assets/Plugins/OpcUaHelper.dll' will not be loaded due to errors:
Unable to resolve reference 'Opc.Ua.Client'. Is the assembly missing or incompatible with the current platform?
Reference validation can be disabled in the Plugin Inspector.
Unable to resolve reference 'Opc.Ua.Core'. Is the assembly missing or incompatible with the current platform?
Reference validation can be disabled in the Plugin Inspector.

二、OPC库文件，下载、导入

使用 OPC UA .NET Standard 库，下载对应的 dll 及所有的依赖（很多很多）。

幸好有大佬整理好放到了 Github ， https://github.com/e-s-unity/org.opc-foundation.ua.net-standard ，去这里下载即可。

下载好的文件目录结构如下：
foundation.ua.net-standard
└───OPCFoundation.NetStandard
└───package.json

在 Unity 中，Add package from disk，选 package.json ，导入到引擎。

导入后，unity 中会报错说找不到巴拉巴拉，能 clear 掉就不用管他。
DirectoryNotFoundException: Could not find a part of the path “D:\org.opc-foundation.ua.net-standard-main\OPCFoundation.NetStandard\Packages\Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.2.1.3\lib\netstandard2.0\Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.dll”

此时已经可以运行了。

三、启动模拟服务

opc ua simulation server

注意，代码只改了 ReadNode 测试，其他的是用别的项目测试的

在这里插入图片描述

四、代码示例

using UnityEngine;
using OpcUaHelper;
using Opc.Ua;
using System;
using System.Threading.Tasks;
using System.Linq;
using Opc.Ua.Client;

public class OpcUaManager : MonoBehaviour
{
    public string serverUrl = "opc.tcp://DESKTOP-HUBTO6G:53530/OPCUA/SimulationServer";
    public string nodeId = "ns=5;s=Random1";

    public NodeId[] nodeIds = new NodeId[]
    {
        new NodeId(20857,1),
        //new NodeId(20858,1),
        //new NodeId(20866,1),
        new NodeId("ns=1;i=20415"),
    };

    OpcUaClient m_OpcUaClient;

    async void Start()
    {
        m_OpcUaClient = new OpcUaClient();

        m_OpcUaClient.UserIdentity = new UserIdentity(new AnonymousIdentityToken());

        try
        {
            await m_OpcUaClient.ConnectServer(serverUrl);
        }
        catch (Exception ex)
        {
            Debug.LogException(ex);
        }

        //Browse(20870, 1);

        //SingleSubscription("AA", 20857, 1);

        //MultySubscription("AA", nodeIds);

        //History();
    }

    private void History()
    {
        var nodeId = new NodeId(20857, 1);

        var startTime = DateTime.Now.AddHours(-1);
        var endTime = DateTime.Now;

        var result = m_OpcUaClient.ReadHistoryRawDataValues<double>($"{nodeId}", startTime, endTime);

        Debug.Log($"count:[{result.Count()}]--------------------------");

        foreach (var item in result)
        {
            Debug.Log(item);
        }

        Debug.Log($"--------------------------");
    }

    private void MultySubscription(string key, NodeId[] ids)
    {
        var tags = ids.Select(x => $"{x}").ToArray();

        m_OpcUaClient.AddSubscription(key, tags, SubCallback);
    }

    private void SingleSubscription(string key, uint value, ushort namespaceIndex)
    {
        var nodeId = new NodeId(value, namespaceIndex);

        Debug.Log($"AddSubscription-->[{key}]:[{nodeId}]");

        m_OpcUaClient.AddSubscription(key, $"{nodeId}", SubCallback);
    }

    private void SubCallback(string key, MonitoredItem monitoredItem, MonitoredItemNotificationEventArgs args)
    {
        Debug.Log($"SubCallback-->[{key}]");

        if (key == "AA")
        {
            MonitoredItemNotification notification = args.NotificationValue as MonitoredItemNotification;
            if (notification != null)
            {
                Debug.Log($"[{monitoredItem.StartNodeId}],[{notification.Value.WrappedValue.Value}]");
            }
        }
    }

    private void Browse(uint value, ushort namespaceIndex)
    {
        var nodeId = new NodeId(value, namespaceIndex);

        Debug.Log($"Browse:[{nodeId}]");

        var results = m_OpcUaClient.BrowseNodeReference($"{nodeId}");

        foreach (var item in results)
        {
            Debug.Log($"{item.NodeClass},{item.BrowseName},{item.DisplayName},{item.NodeId}");
        }

        var list = results
            .Select(x => new NodeId($"{x.NodeId}"))
            .ToArray();

        ReadNodes(list);
    }

    private void OnApplicationQuit()
    {
        Disconnect();
    }

    private async Task<T> ReadNode<T>(string nodeId)
    {
        T result = default;

        try
        {
            result = await m_OpcUaClient.ReadNodeAsync<T>(nodeId);
        }
        catch (Exception ex)
        {
            Debug.LogException(ex);
        }
        finally
        {
            Debug.Log($"[{nodeId}]:[{result}]");
        }

        return result;
    }

    private async void ReadNodes(NodeId[] nodeIds)
    {
        var result = await m_OpcUaClient.ReadNodesAsync(nodeIds);

        for (int i = 0; i < result.Count; i++)
        {
            var dataValue = result[i];

            Debug.Log($"{dataValue.Value.GetType()}-->{dataValue.WrappedValue.TypeInfo}-->{dataValue.WrappedValue.Value}-->{dataValue.Value}");

            //if (dataValue.Value.GetType() == typeof(double))
            //{
            //    Debug.Log("double");
            //}
            //else if (dataValue.Value.GetType() == typeof(bool))
            //{
            //    Debug.Log("bool");
            //}
        }
    }

    private void Disconnect()
    {
        if (m_OpcUaClient.Connected)
        {
            m_OpcUaClient.Disconnect();
        }
    }

    private void OnGUI()
    {
        GUILayout.Label($"Connected:{m_OpcUaClient.Connected}");

        if (GUILayout.Button("Disconnect"))
        {
            Disconnect();
        }

        if (GUILayout.Button("Browse"))
        {
            Browse(20870, 1);
        }

        if (GUILayout.Button("ReadNode"))
        {
            ReadNode<double>(nodeId);
        }

        if (GUILayout.Button("ReadMultyNode"))
        {
            ReadNodes(nodeIds);
        }

        if (GUILayout.Button("SingleSubscription"))
        {
            SingleSubscription("AA", 20857, 1);
        }

        if (GUILayout.Button("MultySubscription"))
        {
            MultySubscription("AA", nodeIds);
        }

        if (GUILayout.Button("RemoveSubscription"))
        {
            if (m_OpcUaClient.Connected)
            {
                m_OpcUaClient.RemoveSubscription("AA");
            }
        }

        if (GUILayout.Button("History"))
        {
            History();
        }
    }
}