本文主要是介绍关于OPC-UA客户端调用服务端方法CallMethod节点的问题，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
在OpcUaClient中可以通过CallMethodByNodeId调用方法节点
//// 摘要:// call a server method//// 参数:// tagParent:// 方法的父节点tag//// tag:// 方法的节点tag//// args:// 传递的参数//// 返回结果:// 输出的结果值public object[] CallMethodByNodeId(string tagParent, string tag, params object[] args);注意，调用方法节点时，必须传入指定的参数类型的值，不能传入可以隐式转化的实参
比如在OpcServer服务器上有个方法节点，方法名为readJob,需要传入两个参数 (byte sourceNumber, short jobNo)，返回一个工作名称string jobName
方法整体描述为 string readJob(byte sourceNumber, short jobNo)
传入的实参 new object[]{1,23};会抛出异常，因1和23在C#中是Int32类型,不是byte,short类型
如果需要调用成功，传入的实参必须是new object[]{(byte)1, (short)23};
一、新建Winform应用程序OpcUaCallMethodDemo，将默认的Form1修改为FormOpcUaCallMethod。
并添加Opc客户端类库的引用以及其他必须相关类库文件。
OpcUaHelper.dll
Opc.Ua.Core.dll
Opc.Ua.Client.dll
二、新建类GumOpcUaClientUtil，用于连接Opc服务已经读写标签，调用Opc方法等
GumOpcUaClientUtil.cs源代码下：
using Opc.Ua;
using OpcUaHelper;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;namespace OpcUaCallMethodDemo
{/// <summary>/// 涂胶OPC客户端:连接OPC服务端，读、写标签操作/// </summary>public class GumOpcUaClientUtil{/// <summary>/// 定义一个操作OPC的客户端对象/// </summary>private static OpcUaClient m_OpcUaClient = new OpcUaClient();/// <summary>/// 连接到Opc服务端/// </summary>/// <param name="serverAddress"></param>/// <param name="enabledAnonymousLogin"></param>/// <param name="loginUserName"></param>/// <param name="loginPassword"></param>/// <returns></returns>public static bool ConnectOpcServer(string serverAddress, bool enabledAnonymousLogin, string loginUserName, string loginPassword, Action<string> LogToShow){bool isConnected = false;if (enabledAnonymousLogin){//匿名登录m_OpcUaClient.UserIdentity = new UserIdentity(new AnonymousIdentityToken());}else{//用户名密码登录m_OpcUaClient.UserIdentity = new UserIdentity(loginUserName, loginPassword);}try{LogToShow($"准备连接OPC服务端【{serverAddress}】，匿名登录【{enabledAnonymousLogin}】，用户名【{loginUserName}】，密码【{loginPassword}】");Task task = m_OpcUaClient.ConnectServer(serverAddress);task.Wait(5000);isConnected = m_OpcUaClient.Connected;//HansCommon.SysMsg.MySystemMsg.LogToShow($"获取到 连接OPC服务端【{serverAddress}】结果：{isConnected}", true);}catch (Exception ex){string exMsg = $"连接OPC服务【{serverAddress}】失败，错误原因：{ex.Message}";LogToShow(exMsg);MessageBox.Show(exMsg, "错误");}return isConnected;}/// <summary>/// 断开OPC服务/// </summary>public static void Disconnect(){m_OpcUaClient.RemoveAllSubscription();m_OpcUaClient.Disconnect();}/// <summary>/// 调用OPC的方法/// </summary>/// <param name="tagParent">方法的父标签路径</param>/// <param name="methodName">方法的标签全路径</param>/// <param name="args">参数列表，没有参数请输入null</param>/// <returns></returns>public static object[] CallMethodNode(Action<string> LogToShow, string tagParent, string methodName, params object[] args) {try{object[] methodResult = m_OpcUaClient.CallMethodByNodeId(tagParent, methodName, args);return methodResult;}catch (Exception ex){MessageBox.Show(ex.Message);LogToShow($"调用OPC的方法时出错{ex.Message}");return null;}}/// <summary>/// 读取某一个标签/// </summary>/// <typeparam name="T"></typeparam>/// <param name="tagName"></param>/// <returns></returns>public static bool ReadTagNode<T>(string tagName, Action<string> LogToShow, out T tResult){tResult = default(T);DataValue dataValue = m_OpcUaClient.ReadNode(new NodeId(tagName));if (dataValue == null || dataValue.WrappedValue == Variant.Null){string exMsg = $"[{tagName}]项读取失败，可能是①未连接的opc服务或者连接已断开.②标签路径或数据类型设置错误，注意：标签名区分大小写.③没有权限读取数据";LogToShow(exMsg);return false;}else{object objValue = dataValue.WrappedValue.Value;tResult = (T)objValue;}return true;}public static object ReadTagNode(string tagName, Action<string> LogToShow){DataValue dataValue = m_OpcUaClient.ReadNode(new NodeId(tagName));if (dataValue == null || dataValue.WrappedValue == Variant.Null){string exMsg = $"[{tagName}]项读取失败，可能是①未连接的opc服务或者连接已断开.②标签路径或数据类型设置错误，注意：标签名区分大小写.③没有权限读取数据";LogToShow(exMsg);return null;}else{object objValue = dataValue.WrappedValue.Value;return objValue;}}/// <summary>/// 批量读取/// </summary>/// <typeparam name="T"></typeparam>/// <param name="tagNames"></param>/// <returns></returns>public static List<T> ReadNodeList<T>(string[] tagNames, Action<string> LogToShow){try{List<T> list = m_OpcUaClient.ReadNodes<T>(tagNames);return list;}catch (Exception ex){string exMsg = $"批量读取节点集合出错【{string.Join(",", tagNames)}】，可能是①未连接的opc服务或者连接已断开.②存在标签路径或数据类型设置错误，注意：标签名区分大小写.③没有权限读取数据.异常信息：{ex.Message}";LogToShow(exMsg);throw new Exception(exMsg);}}/// <summary>/// 为指定的标签写入指定类型的值。注意：【写入的标签名 和 写入的值的类型一定要和服务端保持一致】/// </summary>/// <typeparam name="T"></typeparam>/// <param name="tagName"></param>/// <param name="value"></param>/// <returns></returns>public static bool WriteTagNode<T>(string tagName, Action<string> LogToShow, T value){try{return m_OpcUaClient.WriteNode(tagName, value);}catch (Exception ex){string exMsg = $"【{tagName}】项写入【{value}】失败，【写入的标签名 和 写入的值的类型一定要和服务端保持一致】.异常信息：{ex.Message}";LogToShow(exMsg);throw new Exception(exMsg);}}}
}
三、窗体FormOpcUaCallMethod设计器代码如下：
文件FormOpcUaCallMethod.Designer.cs
namespace OpcUaCallMethodDemo
{partial class FormOpcUaCallMethod{/// <summary>/// 必需的设计器变量。/// </summary>private System.ComponentModel.IContainer components = null;/// <summary>/// 清理所有正在使用的资源。/// </summary>/// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param>protected override void Dispose(bool disposing){if (disposing && (components != null)){components.Dispose();}base.Dispose(disposing);}#region Windows 窗体设计器生成的代码/// <summary>/// 设计器支持所需的方法 - 不要修改/// 使用代码编辑器修改此方法的内容。/// </summary>private void InitializeComponent(){this.rtxtMessage = new System.Windows.Forms.RichTextBox();this.btnConnect = new System.Windows.Forms.Button();this.SuspendLayout();// // rtxtMessage// this.rtxtMessage.Location = new System.Drawing.Point(249, 12);this.rtxtMessage.Name = "rtxtMessage";this.rtxtMessage.ReadOnly = true;this.rtxtMessage.Size = new System.Drawing.Size(700, 495);this.rtxtMessage.TabIndex = 0;this.rtxtMessage.Text = "";// // btnConnect// this.btnConnect.Location = new System.Drawing.Point(27, 72);this.btnConnect.Name = "btnConnect";this.btnConnect.Size = new System.Drawing.Size(152, 36);this.btnConnect.TabIndex = 1;this.btnConnect.Text = "连接Opc服务端并测试";this.btnConnect.UseVisualStyleBackColor = true;this.btnConnect.Click += new System.EventHandler(this.btnConnect_Click);// // FormOpcUaCallMethod// this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;this.ClientSize = new System.Drawing.Size(1018, 531);this.Controls.Add(this.btnConnect);this.Controls.Add(this.rtxtMessage);this.Name = "FormOpcUaCallMethod";this.Text = "使用OpcUaCallMethod调用OpcServer的方法节点";this.ResumeLayout(false);}#endregionprivate System.Windows.Forms.RichTextBox rtxtMessage;private System.Windows.Forms.Button btnConnect;}
}窗体FormOpcUaCallMethod代码如下：
文件FormOpcUaCallMethod.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;namespace OpcUaCallMethodDemo
{public partial class FormOpcUaCallMethod : Form{public FormOpcUaCallMethod(){InitializeComponent();}/// <summary>/// 显示推送消息/// </summary>/// <param name="msg"></param>private void DisplayMessage(string msg){this.BeginInvoke(new Action(() =>{if (rtxtMessage.TextLength > 409600){rtxtMessage.Clear();}rtxtMessage.AppendText($"{DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff")}->{msg}\n");rtxtMessage.ScrollToCaret();}));}private void btnConnect_Click(object sender, EventArgs e){//连接OPC服务端string serverAddress = "opc.tcp://192.168.1.20:48030";bool isRun = GumOpcUaClientUtil.ConnectOpcServer(serverAddress, false, "admin", "password123456", DisplayMessage);DisplayMessage($"连接OPC服务端【{serverAddress}】：{(isRun ? "成功" : "失败")}");if (!isRun){DisplayMessage($"连接OPC服务端【{serverAddress}】失败,无法启动");return;}string parentNodeTag = "ns=2;s=A.B.C.ParentTag";string methodNode = "ns=2;s=A.B.C.ParentTag.readJob";//在OpcServer服务器上有个方法节点，方法名为readJob,需要传入两个参数 (byte sourceNumber, short jobNo)，返回一个工作名称string jobName//方法整体描述为 string readJob(byte sourceNumber, short jobNo)short jobNo = 12;object[] resultArray = GumOpcUaClientUtil.CallMethodNode(DisplayMessage, parentNodeTag, methodNode, new object[] { (byte)1, jobNo });if (resultArray == null || resultArray.Length < 1){DisplayMessage($"读取readJob节点出错，低于1个元素，当前工作编号为【{jobNo}】");}else{DisplayMessage($"读取readJob节点成功，返回信息【{resultArray[0]}】，当前工作编号为【{jobNo}】");}}}
}
四、测试如图：
【没有连接Opc服务端】
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