c# - SerialPort.DataReceived 返回奇怪的结果

Question

我目前正在使用一种称为 Fluke 5500A 多产品校准设备的设备。我用 C# 编写了一个小程序来与它交互并了解有关它如何工作的更多信息，但不幸的是 SerialPort.DataReceived 给了我一些非常奇怪的结果。该程序不长，所以我将在此处完整发布它:

class Program
{
    static public bool isExecuting = true;
    static private string serialCommand;
    static private string dataReceived;

    static void Main(string[] args)
    {
        SerialPortConnection serialPort = new SerialPortConnection();

        serialPort.OpenSerialConnection();

        while (isExecuting == true)
        {
            Console.WriteLine("Enter a command or type q to quit.");
            serialCommand = Console.ReadLine().ToUpper();

            if (serialCommand == "Q")
                isExecuting = false;
            else if (serialCommand == "CLEAR")
                Console.Clear();
            else
            {
                dataReceived = serialPort.WriteSerialConnection(serialCommand);
                Console.WriteLine(dataReceived);
            }
        }

        serialPort.CloseSerialConnection();
    }
}

还有我的 SerialPortConnection 类:

public class SerialPortConnection
{
    private SerialPort serialPort;
    private string dataReceived = "none";

    public SerialPortConnection(string comPort = "Com3", int baud = 9600, System.IO.Ports.Parity parity = System.IO.Ports.Parity.None, int dataBits = 8, System.IO.Ports.StopBits stopBits = System.IO.Ports.StopBits.One)
    {
        serialPort = new SerialPort(comPort, baud, parity, dataBits, stopBits);
    }

    public void OpenSerialConnection()
    {
        try
        {
            serialPort.Open();
        }
        catch (Exception e)
        {
            Console.Write("\nError");
            Console.Write(e);
        }
    }

    public string WriteSerialConnection(string SerialCommand)
    {
        try
        {
            serialPort.Write(String.Format(SerialCommand + "\r"));
            dataReceived = serialPort.ReadExisting();
            return dataReceived;
        }
        catch (Exception e)
        {
            Console.Write("\nError");
            Console.Write(e);
            return "Execution Unsuccessful";
        }
    }

    public void CloseSerialConnection()
    {
        try 
        {
            serialPort.Close();
        }
        catch (Exception e)
        {
            Console.Write("\nError");
            Console.Write(e);
        }
    }
}

我目前的问题是控制台的输出看起来像这样:

Enter a command or type q to quit.
*IDN?

Enter a command or type q to quit.
OUT 50V <-- Command input
*IDN? <-- Previous command echoed back
FLUKE,5500A,8030005,2.61+1.3+2.0+* <-- Data received from previous command
161>
Enter a command or type q to quit.
OPER
OUT 50V
162>
Enter a command or type q to quit.
STBY
OPER
163>
Enter a command or type q to quit.
*RST
STBY
164>
Enter a command or type q to quit.

命令执行得很好，但控制台的输出似乎是最后执行的命令以及该命令返回的任何数据。我不知道为什么会这样。

编辑:

感谢 Robert P 的回答，我实现了以下代码:

var received = "";
bool isReading = true;
while (isReading == true)
{
    try
    {
        received += serialPort.ReadExisting();
        if (received.Contains('>'))
            isReading = false;
    }
    catch (Exception e)
    {
    }
}
Console.WriteLine(received);

Answer 1

你的问题的一部分是串行通信远非即时的。 .ReadExisting() 方法从 SerialPort 对象的缓冲区中提取数据，但不确保设备已完成发出命令。可以这样想:

+----+            +----------+           +------------+
|Your|--Command-->|Serial    |---UART--->|    Device  |
|Code|            |Port Obj  |           |            |
+----+            +----------+           +------------+

+----+            +----------+           +------------+
|Your|<--Read-----|Serial    |           |Device      |
|Code| (is empty) |          |           |(processing)|
+----+            +----------+           +------------+

+----+            +----------+           +------------+
|Your|            |Serial    |<-response-|Device      |
|Code|            |(has data)|           |(responding)|
+----+            +----------+           +------------+

+----+            +----------+           +------------+
|Your|--Command2->|Serial    |---UART--->|    Device  |
|Code|            |(has data)|           |            |
+----+            +----------+           +------------+

+----+            +----------+           +------------+
|Your|<--Read-----|Serial    |           |Device      |
|Code| (previous  |          |           |(processing)|
+----+  response) +----------+           +------------+

相反，在发送下一个命令之前寻找模式、 token 或其他识别标记以了解传输已完成。继续阅读(预计超时 - 它们会作为异常抛出!)直到您知道您已收到完整的回复。在这种情况下，> 字符可能表示“准备好接受更多输入”。您也可以将其解释为“响应已完成”。