无人地磅自助机开发总结（五）物理开关，8路继电器

1.这个开关直接监听串口是没有用的，需要向串口发送数据，然后再监听判断哪一个按钮被按下

2.开关的配置文件配置在xml文件里

3.读取xml类

 public class XmlHelper
    {
        public static string GetElementByName(string xmlFileName, string tagName)
        {
            try
            {
                string result = null;
                XmlDocument doc = new XmlDocument();
                doc.Load(xmlFileName);
                XmlNodeList nodes = doc.GetElementsByTagName(tagName);
                foreach (XmlNode v in nodes)
                {
                    result = v.InnerText;
                }
                return result;
            }
            catch
            {
                throw new Exception("打开文件错误");
            }
        }
    }

4.打开开关串口

  SerialPort sport = new SerialPort();

   if (sport.IsOpen == true)
            {
                sport.Close();
            }
            string sIniFile = appPath + "wmsconfig" + "\" + "SwitchSetting.xml";
            if (File.Exists(sIniFile))
            {
                sport.BaudRate = Convert.ToInt32(XmlHelper.GetElementByName(sIniFile, "BaudRate"));
                sport.DataBits = Convert.ToInt32(XmlHelper.GetElementByName(sIniFile, "DataBits"));
                sport.StopBits = (StopBits)Convert.ToInt32(XmlHelper.GetElementByName(sIniFile, "StopBits"));
                sport.Parity = (Parity)Convert.ToInt32(XmlHelper.GetElementByName(sIniFile, "Parity"));
                var portName = XmlHelper.GetElementByName(sIniFile, "PortName");

                if (null != portName)
                    sport.PortName = portName;
            }
            sport.BaudRate = 9600;
            sport.DataBits = 8;
            sport.StopBits = StopBits.One;
            //sport.PortName = "COM1";
            sport.Parity = Parity.None;
            try
            {
                sport.Open();//打开串口
                sport.DtrEnable = true;//设置DTR为高电平
                sport.RtsEnable = true;//设置RTS位高电平               
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

5.写一个定时器不停的向串口发送数据，监听串口

DispatcherTimer timer;
timer = new DispatcherTimer();
timer.Interval = TimeSpan.FromMilliseconds(1000);
timer.Tick += timer2_Tick;
timer.Start();
sport.DataReceived -= new SerialDataReceivedEventHandler(serialPort_DataReceived);//订阅委
sport.DataReceived += new SerialDataReceivedEventHandler(serialPort_DataReceived);//订阅委

 private void timer2_Tick(object sender, EventArgs e)
        {
            if (sport.IsOpen == true)
            {
                strReceiveMessage = "";
                byte[] sendData = new byte[] { 0x21, 0x02, 0x00, 0x00, 0x00, 0x08, 0x7E, 0xAC };
                ////发送数据
                sport.Write(sendData, 0, sendData.Length);
            }

        }

6.判断是开始按钮还是结束按钮

  //接收按钮数据事件
        private void serialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            Thread.Sleep(100);  //（毫秒）等待一定时间，确保数据的完整性 int len        
            int len = sport.BytesToRead;
            string receivedata = string.Empty;
            if (len != 0)
            {
                byte[] buff = new byte[len];
                sport.Read(buff, 0, len);
                for (int i = 0; i < buff.Length; i++)
                {
                    strReceiveMessage += buff[i].ToString("X2");  //16进制显示  
                }
                ts2 = new TimeSpan(DateTime.Now.Ticks);
                            
                if (strReceiveMessage!=null)
                {
                    if (strReceiveMessage.Contains("21020104AB8B"))
                    {// MessageBox.Show("开始按钮");
                      
                    }
　　　　　　　　  }
　　　　　　 }
　　　　}