串口通讯问题C＃

Question

我的控制台程序遇到了一些麻烦。我试图从条码扫描器的串行连接中检索数据。

问题是： - 第一次阅读是完美的; - 第二次读取结​​果不正确，除非我等待大约一分钟。

下面是代码：

using System; 
using System.IO.Ports; 

class PortDataReceived 
{ 

    public static void Main() 
    { 
     SerialPort mySerialPort = new SerialPort("COM10"); 

     mySerialPort.BaudRate = 9600; 
     mySerialPort.Parity = Parity.None; 
     mySerialPort.StopBits = StopBits.One; 
     mySerialPort.DataBits = 8; 
     mySerialPort.Handshake = Handshake.RequestToSend; 

     mySerialPort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler); 

     mySerialPort.Open(); 

     Console.WriteLine("Press any key to continue..."); 
     Console.WriteLine(); 
     Console.ReadKey(); 

     mySerialPort.Close(); 

    } 

    private static void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e) 
    { 
     SerialPort sp = (SerialPort)sender; 
     string indata = sp.ReadExisting(); 
     Console.WriteLine("Data Received:"); 
     Console.WriteLine(indata);     
    } 
} 

这里是2的结果，而不从第一等待足够的时间来第二次读取同一条码的读取：

Press any key to continue... 
Data Received: 
229000400718 
Data Received: 
2 
Data Received: 
2 
Data Received: 
9 
Data Received: 
0 
Data Received: 
0 
Data Received: 
0 
Data Received: 
4 
Data Received: 
0 
Data Received: 
0 
Data Received: 
7 
Data Received: 
1 
Data Received: 
8 

有什么建议？

提前致谢！

Answer 1

您需要有结束字符才能知道您的消息何时完成。大多数人使用\r\n (13,10)并从串行端口读取到行尾（即\ r \ n）。

您正在为每个角色获得一个事件并快速阅读它。

Answer 2

您需要某种计时器来检查正在读取的多个字符是否是单个读取的一部分，或者它们是否是两次不同的扫描。第二次扫描的事件触发之间的时间可能很短，只需在事件触发后设置一个计时器即可启动，如果在下一个事件之前到期，那么它就是条形码的末尾，如果没有将读取附加到前一个事件（使用某种缓冲区）。

Answer 3

看来，第二次读取的数据来自于焦炭的焦炭，所以我会使用StringBuilder B和附加输入数据，直到一个有效的条形码接收和（即检查对数据库的有效性）

保存在b

我建议是这样的：

private static void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e) 
{ 
    SerialPort sp = (SerialPort)sender; 
    StringBuilder b = new StringBuilder(); 

    while(!IsValidBarcode(b.ToString())) 
    { 
     b.Append(sp.ReadExisting()); 
    } 

    Console.WriteLine("Data Received:"); 
    Console.WriteLine(b.ToString()); 
} 

private static Boolean IsValidBarcode(String s) 
{ 
    if (String.IsNullOrEmpty(s)) return false; 

    // (1) Query a database for expected barcodes ... 
    // (2) Check s for Start-Stop-Characters ... 
    // (3) Query the device for completed barcode ... 

    throw new NotImplementedException(); 
} 

或本

private static void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e) 
{ 
    SerialPort sp = (SerialPort)sender; 
    StringBuilder b = new StringBuilder(); 

    Thread.Sleep(1000);  // 1 second delay for testing purposes 

    b.Append(sp.ReadExisting()); 

    Console.WriteLine("Data Received:"); 
    Console.WriteLine(b.ToString()); 
} 

Answer 4

卢卡Pillin，我刚才已经包括了Thread.Sleep 3秒，它解决了问题

using System; 
using System.Threading; 
using System.IO.Ports; 

class PortDataReceived 
{ 

    public static void Main() 
    { 
     SerialPort mySerialPort = new SerialPort("COM2"); 

     mySerialPort.BaudRate = 9600; 
     mySerialPort.Parity = Parity.None; 
     mySerialPort.StopBits = StopBits.One; 
     mySerialPort.DataBits = 8; 
     mySerialPort.Handshake = Handshake.RequestToSend; 

     mySerialPort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler); 

     mySerialPort.Open(); 

     Console.WriteLine("Press any key to continue..."); 
     Console.WriteLine(); 
     Console.ReadKey(); 

     mySerialPort.Close(); 

    } 

    private static void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e) 
    { 
    // 
     string indata = string.Empty; 
     SerialPort sp = (SerialPort)sender; 
     **Thread.Sleep(3000);** 
       indata = sp.ReadExisting(); 


     Console.WriteLine("Data Received:"); 
     Console.WriteLine(indata); 
    } 
}