如何做到稳健的SerialPort编程.NET / C＃？ [英] How to do robust SerialPort programming with .NET / C#?

问题描述

我正在写一个Windows服务用于与串行磁条读取器和中继电路板（访问控制系统）。

I'm writing a Windows Service for communication with a Serial Mag-stripe reader and a relay board (access control system).

我碰到的问题，其中的code停止工作（我得到的IOExceptions）陆续程序中断的过程中打开同一串行端口作为我的服务。

I run into problems where the code stops working (i get IOExceptions) after another program has "interrupted" the process by opening the same serial port as my service.

的code部分如下：

public partial class Service : ServiceBase
{
	Thread threadDoorOpener;
	public Service()
	{
		threadDoorOpener = new Thread(DoorOpener);
	}
	public void DoorOpener()
	{
		while (true)
		{
			SerialPort serialPort = new SerialPort();
			Thread.Sleep(1000);
			string[] ports = SerialPort.GetPortNames();
			serialPort.PortName = "COM1";
			serialPort.BaudRate = 9600;
			serialPort.DataBits = 8;
			serialPort.StopBits = StopBits.One;
			serialPort.Parity = Parity.None;
			if (serialPort.IsOpen) serialPort.Close();
			serialPort.Open();
			serialPort.DtrEnable = true;
			Thread.Sleep(1000);
			serialPort.Close();
		}
	}
	public void DoStart()
	{
		threadDoorOpener.Start();
	}
	public void DoStop()
	{
		threadDoorOpener.Abort();
	}
	protected override void OnStart(string[] args)
	{
		DoStart();
	}
	protected override void OnStop()
	{
		DoStop();
	}
}

我的样本程序成功启动工作线程，和DTR的开/关和提高导致我的磁条读写器上电（等待1秒），关闭（等待1秒）等。

My sample program successfully starts the work-thread, and the opening/closing and raising of DTR causes my Mag-stripe reader to power up (wait 1sec), shut down (wait 1 sec) and so on.

如果我启动超级终端，并连接到同一个COM端口，超级终端告诉我的端口正在使用中。如果我反复美元的超级p $ PSS进入，尝试重新打开 该端口将经过几次重试成功。

If I launch HyperTerminal and connects to the same COM port, HyperTerminal tells me the port is currently in use. If i repeatedly press ENTER in HyperTerminal, to try to reopen the port it will succeed after a few retries.

这已经造成的IOExceptions我的工作线程，预期的效果。然而，即使我关闭超级终端，我仍然会得到相同的IOException的我的工作线程。唯一的治疗实际上是重新启动计算机。

This has the effect of causing IOExceptions in my work-thread, which is expected. However, even if I close down HyperTerminal, i still get the same IOException in my work-thread. The only cure is actually to restart the computer.

其他方案（未使用.NET库端口的访问）似乎在这一点上，通常工作

Other programs (which is not using .NET libraries for port-access) seem to work normally at this point.

任何想法是什么原因造成的？

Any ideas as to what is causing this?

推荐答案

@thomask

是的，超级终端将实际上在SetCommState的DCB，这可以解释为大多数抛出的SerialPort对象的IOExceptions的启用fAbortOnError。某些电脑/手持设备也有对错误标志中止默认打开的UART - 所以它的当务之急是一个串行口的初始化程序中清除（微软忽视了这样做）。我写了一篇长文最近来解释这个更详细（见这个，如果​​你'再有兴趣）。

Yes, Hyperterminal does in fact enable fAbortOnError in SetCommState's DCB, which explains for most of the IOExceptions thrown by the SerialPort object. Some PCs / handhelds also have UARTs that have the abort on error flag turned on by default - so it's imperative that a serial port's init routine clears it (which Microsoft neglected to do). I wrote a long article recently to explain this in greater detail (see this if you're interested).

这篇关于如何做到稳健的SerialPort编程.NET / C＃？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！