在 C# 中访问 COM10 或更大的端口

问题描述

我正在使用 Visual Studio 2010 并使用 C# (.NET 3.5) 进行编程.

I am using Visual Studio 2010 and programing in C# (.NET 3.5).

我想从 COM10 写入/读取数据.

I want to write/read data from COM10.

这是一个简单的代码:

static void Main(string[] args)
{
    String Portname = String.Empty;

    /* List out all COM ports present on the computer. */
    foreach (string ports in SerialPort.GetPortNames())
    {
        Console.WriteLine(ports);
        /* If COM10 exists, copy the name for further use. */
        if (ports == "COM10")
        {
            Portname = ports; //I also tried this: "\\.\\COM10";
        }
    }
    /* If COM10 not found, return */
    if (Portname == String.Empty)
    {
        Console.WriteLine("Exiting");
        return;
    }

    SerialPort Port = new SerialPort(Portname,
                                     9600,          // Baudrate
                                     Parity.None,   //Parity
                                     8,             //DataBits
                                     StopBits.One); //Stop Bits

    Port.Open();

    for (int count = 0; count < 5; count++)
    {
        Port.WriteLine("\nHello");
    }
    Port.Close();

    while (true);
}

每当我在 SerialPort Port = new SerialPort(Portname,9600,.....); 中使用 Portname 作为COM10"时，它都会给出一个错误为

Whenever I use Portname as "COM10" in SerialPort Port = new SerialPort(Portname,9600,.....);, it gives an error as

端口'COM10'不存在

在Port.Open()上，如果COM10不存在，它甚至不应该到达命令Port.Open().

On Port.Open(), it should not even reach to command Port.Open() if COM10 doesn't exist.

另一种方式，我尝试将 Portname 设为\.\COM10".它给出了一个错误

Another way, I tried Portname as "\.\COM10". It gives an error as

给定的端口名称不以 COM/com 开头或未解析为有效的串行端口.

任何大于 COM9 的端口号都会发生这种情况.

This happens with any port number greater than COM9.

有出路吗?

推荐答案

不能打开大于 10 的串口是因为 FCL SerialPort 实现如下示例:

The reason why you can't open a serial port greater than 10 is because FCL SerialPort implemented like in the following sample:

[MonitoringDescription("PortName")]
[Browsable(true)]
[DefaultValue("COM1")]
public string PortName
{
  [TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")] get
  {
    return this.portName;
  }
  set
  {
    if (value == null)
      throw new ArgumentNullException("PortName");
    if (value.Length == 0)
      throw new ArgumentException(SR.GetString("PortNameEmpty_String"), "PortName");
    if (value.StartsWith("\\\\", StringComparison.Ordinal))
      throw new ArgumentException(SR.GetString("Arg_SecurityException"), "PortName");
    if (this.IsOpen)
      throw new InvalidOperationException(SR.GetString("Cant_be_set_when_open", new object[1]
      {
        (object) "PortName"
      }));
    else
      this.portName = value;
  }
}

如您所见，标准 SerialPort 不允许您在端口名称中使用 \\.\ 符号.我不知道他们为什么这样做.使用 \\.\ 符号，可以打开大于 10 的端口.因此，唯一的方法是实现您自己的 SerialPort 组件.

As you see, standard SerialPort does not allow you to use \\.\ notation in the port name. And I don't know why they did this. With \\.\ notation, ports greater than 10 can be opened. So, the only way is to implement your own SerialPort component.

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