PLC數據訪問

PLC是很多機床設備上都有的控制中心，和PLC通信是很多做工廠管理系統的必經之路。

一年前有個項目需要和PLC（西門子S200）通信，不僅讀取里面的數據，還需要寫數據需要控制機床的運行，當時不大了解，由於設備比較老，沒有以太網模塊，還是在設備供應商的提示下用串口rs485聯通pc，查資料了解modbus協議，完全手寫按照modbus協議和PLC通信，最后總算了磕磕絆絆完成項目，后來還有各種超時異常造成機床運行錯誤，哎。

現在是第二個階段，在老前輩的帶領下，雖說對PLC下位機程序還是了解甚少，但是對如何與PLC通信方面比以前了解更多。由於市面上PLC的品牌和型號比較多，如果是要求各種PLC都和服務器連接並受控制或集中管理，基本上都會安裝以太網擴展卡，然后在服務器上部署opc服務器，opc服務器的種類也比較多，西門子有自己的opc服務器，第三方的opc服務器也很好，能兼容很多種PLC種類和型號，自帶的各種驅動，就現在這個項目來說用的是kepserver，用這個管理軟件的人很多，只要知道想要的數據在PLC的正確地址，在kepserver做個配置即可。

剩余的事情就是寫程序，從kepserver里存取數據，就像訪問數據庫一樣，OPCDAAuto是個不錯的選擇，現在我用的dotnet，網上down一個OPCDAAuto.dll直接使用，如何使用OPCDAAuto.dll網上也有很多例子。下面是簡單例子：

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(5000);

        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 = "關機";

        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 = "已連接到-" + _kepServer.ServerName;
                }
                else
                {
                    //這里你可以根據返回的狀態來自定義顯示信息，請查看自動化接口API文檔
                    tsslServerState.Text = "狀態：" + _kepServer.ServerState;
                }
            }
            catch (Exception err)
            {
                MessageBox.Show("連接遠程服務器出現錯誤：" + 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", 1001);
                _omronStart = _groupOmron.OPCItems.AddItem("Channel_Omron.Device1.Start", 1002);
                _omronWarn = _groupOmron.OPCItems.AddItem("Channel_Omron.Device1.Warn", 1003);

                _groupSiemens = _kepGroups.Add("siemens");
                _siemensQty = _groupSiemens.OPCItems.AddItem("Channel_Siemens.Device1.Qty", 2001);
                _siemensStart = _groupSiemens.OPCItems.AddItem("Channel_Siemens.Device1.Start", 2002);
                _siemensWarn = _groupSiemens.OPCItems.AddItem("Channel_Siemens.Device1.Warn", 2003);

                _timer.Elapsed += (o, args) =>
                {
                    _timer.Enabled = false;
                    try
                    {
                        object value = null;
                        object quality = null;
                        object timestamp = null;
                        _omronQty.Read(1, out value, out quality, out timestamp);
                        _logger.Debug(_omronQty.ItemID + "=" + value);
                        var yazhu7Qty = value;
                        _omronStart.Read(1, out value, out quality, out timestamp);
                        _logger.Debug(_omronStart.ItemID + "=" + value);
                        value = value ?? true;
                        var yazhu7Start = value.Equals(false) ? open : close;
                        _omronWarn.Read(1, out value, out quality, out timestamp);
                        _logger.Debug(_omronWarn.ItemID + "=" + value);
                        SaveData("Y7", yazhu7Start, yazhu7Qty);/*保存壓鑄7機台數據*/

                        _siemensQty.Read(1, out value, out quality, out timestamp);
                        _logger.Debug(_siemensQty.ItemID + "=" + value);
                        var yazhu11Qty = value;
                        _siemensStart.Read(1, out value, out quality, out timestamp);
                        _logger.Debug(_siemensStart.ItemID + "=" + value);
                        value = value ?? true;
                        var yazhu11Start = value.Equals(false) ? open : close;
                        _siemensWarn.Read(1, out value, out quality, out timestamp);
                        _logger.Debug(_siemensWarn.ItemID + "=" + value);
                        SaveData("Y11", yazhu11Start, yazhu11Qty);/*保存壓鑄11機台數據*/
                    }
                    catch (Exception exception)
                    {
                        _logger.Error(exception);
                    }
                    finally
                    {
                        _timer.Enabled = true;
                    }
                };
                _timer.Enabled = true;
                btnConnLocalServer.Enabled = false;
                
            }
            catch (Exception err)
            {
                MessageBox.Show("初始化出錯：" + 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 = 0;
                btnConnLocalServer.Enabled = true;
            }
            catch (Exception err)
            {
                MessageBox.Show("枚舉本地OPC服務器出錯：" + err.Message, "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }

        }
    }
}