PLC数据访问

PLC是很多机床设备上都有的控制中心，和PLC通信是很多做工厂管理系统的必经之路。

一年前有个项目需要和PLC（西门子S200）通信，不仅读取里面的数据，还需要写数据需要控制机床的运行，当时不大了解，由于设备比较老，没有以太网模块，还是在设备供应商的提示下用串口rs485联通pc，查资料了解modbus协议，完全手写按照modbus协议和PLC通信，最后总算了磕磕绊绊完成项目，后来还有各种超时异常造成机床运行错误，哎。

现在是第二个阶段，在老前辈的带领下，虽说对PLC下位机程序还是了解甚少，但是对如何与PLC通信方面比以前了解更多。由于市面上PLC的品牌和型号比较多，如果是要求各种PLC都和服务器连接并受控制或集中管理，基本上都会安装以太网扩展卡，然后在服务器上部署opc服务器，opc服务器的种类也比较多，西门子有自己的opc服务器，第三方的opc服务器也很好，能兼容很多种PLC种类和型号，自带的各种驱动，就现在这个项目来说用的是kepserver，用这个管理软件的人很多，只要知道想要的数据在PLC的正确地址，在kepserver做个配置即可。

剩余的事情就是写程序，从kepserver里存取数据，就像访问数据库一样，OPCDAAuto是个不错的选择，现在我用的dotnet，网上down一个OPCDAAuto.dll直接使用，如何使用OPCDAAuto.dll网上也有很多例子。下面是简单例子：

 using System;
 using System.Windows.Forms;
 using log4net;
 using OPCAutomation;

 namespace OpcDaAutoTest
 {
     public partial class FormReader : Form
     {
         private ILog _logger = LogManager.GetLogger(typeof(Form1));
         private System.Timers.Timer _timer = new System.Timers.Timer();

         private OPCGroups _kepGroups = null;
         private OPCGroup _groupOmron = null;
         private OPCItem _omronQty = null;
         private OPCItem _omronStart = null;
         private OPCItem _omronWarn = null;
         private OPCGroup _groupSiemens = null;
         private OPCItem _siemensQty = null;
         private OPCItem _siemensStart = null;
         private OPCItem _siemensWarn = null;

         const string open = "正常";
         const string close = "关机";

         public FormReader()
         {
             InitializeComponent();
         }

         private void FormReader_Load(object sender, EventArgs e)
         {
             GetLocalServer();
             btnConnLocalServer.Click += btnConnLocalServer_Click;
             FormClosing += OnFormClosing;
         }

         private void OnFormClosing(object sender, FormClosingEventArgs formClosingEventArgs)
         {
             if (_kepServer != null)
             {
                 _kepServer.Disconnect();
                 _kepServer = null;
             }
         }

         private bool ConnectRemoteServer(string remoteServerName)
         {
             try
             {
                 _kepServer.Connect(remoteServerName);

                 if (_kepServer.ServerState == (int)OPCServerState.OPCRunning)
                 {
                     tsslServerState.Text = "已连接到-" + _kepServer.ServerName;
                 }
                 else
                 {
                     //这里你可以根据返回的状态来自定义显示信息，请查看自动化接口API文档
                     tsslServerState.Text = "状态：" + _kepServer.ServerState;
                 }
             }
             catch (Exception err)
             {
                 MessageBox.Show("连接远程服务器出现错误：" + err.Message, "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                 return false;
             }
             return true;
         }
         private void btnConnLocalServer_Click(object sender, EventArgs e)
         {
             try
             {
                 if (!ConnectRemoteServer(cmbServerName.Text))
                 {
                     return;
                 }

                 _kepGroups = _kepServer.OPCGroups;
                 _groupOmron = _kepGroups.Add("omron");
                 _omronQty = _groupOmron.OPCItems.AddItem("Channel_Omron.Device1.Qty", );
                 _omronStart = _groupOmron.OPCItems.AddItem("Channel_Omron.Device1.Start", );
                 _omronWarn = _groupOmron.OPCItems.AddItem("Channel_Omron.Device1.Warn", );

                 _groupSiemens = _kepGroups.Add("siemens");
                 _siemensQty = _groupSiemens.OPCItems.AddItem("Channel_Siemens.Device1.Qty", );
                 _siemensStart = _groupSiemens.OPCItems.AddItem("Channel_Siemens.Device1.Start", );
                 _siemensWarn = _groupSiemens.OPCItems.AddItem("Channel_Siemens.Device1.Warn", );

                 _timer.Elapsed += (o, args) =>
                 {
                     _timer.Enabled = false;
                     try
                     {
                         object value = null;
                         object quality = null;
                         object timestamp = null;
                         _omronQty.Read(, out value, out quality, out timestamp);
                         _logger.Debug(_omronQty.ItemID + "=" + value);
                         var yazhu7Qty = value;
                         _omronStart.Read(, out value, out quality, out timestamp);
                         _logger.Debug(_omronStart.ItemID + "=" + value);
                         value = value ?? true;
                         var yazhu7Start = value.Equals(false) ? open : close;
                         _omronWarn.Read(, out value, out quality, out timestamp);
                         _logger.Debug(_omronWarn.ItemID + "=" + value);
                         SaveData("Y7", yazhu7Start, yazhu7Qty);/*保存压铸7机台数据*/

                         _siemensQty.Read(, out value, out quality, out timestamp);
                         _logger.Debug(_siemensQty.ItemID + "=" + value);
                         var yazhu11Qty = value;
                         _siemensStart.Read(, out value, out quality, out timestamp);
                         _logger.Debug(_siemensStart.ItemID + "=" + value);
                         value = value ?? true;
                         var yazhu11Start = value.Equals(false) ? open : close;
                         _siemensWarn.Read(, out value, out quality, out timestamp);
                         _logger.Debug(_siemensWarn.ItemID + "=" + value);
                         SaveData("Y11", yazhu11Start, yazhu11Qty);/*保存压铸11机台数据*/
                     }
                     catch (Exception exception)
                     {
                         _logger.Error(exception);
                     }
                     finally
                     {
                         _timer.Enabled = true;
                     }
                 };
                 _timer.Enabled = true;
                 btnConnLocalServer.Enabled = false;

             }
             catch (Exception err)
             {
                 MessageBox.Show("初始化出错：" + err.Message, "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Warning);
             }
         }

         private void SaveData(string machineNo, string start, object qty)
         {
             try
             {
                 using (var db = DbAccess.GetDbContext())
                 {
                     if (start.Equals(close))
                     {
                         db.Sql("update kbequipment set running=@0 where type=0 and name=@1")
                             .Parameters(start, machineNo)
                             .Execute();
                     }
                     else
                     {
                         db.Sql("update kbequipment set running=@0, status=@1 where type=0 and name=@2")
                             .Parameters(start, qty, machineNo)
                             .Execute();
                     }
                 }
             }
             catch (Exception e)
             {
                 _logger.Error(e.Message, e);
             }
         }

         private OPCServer _kepServer;
         private void GetLocalServer()
         {
             try
             {
                 _kepServer = new OPCServer();
                 object serverList = _kepServer.GetOPCServers(Environment.MachineName);

                 foreach (string turn in (Array)serverList)
                 {
                     cmbServerName.Items.Add(turn);
                 }

                 cmbServerName.SelectedIndex = ;
                 btnConnLocalServer.Enabled = true;
             }
             catch (Exception err)
             {
                 MessageBox.Show("枚举本地OPC服务器出错：" + err.Message, "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Warning);
             }

         }
     }
 }