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(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 = "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", 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);/*保存压铸7机台数据*/

                        _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 = 0;
                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);
            }

        }
    }
}