Windows XP 嵌入式版本上 System.IO.IOException 的原因是什么?

问题描述

我在 Windows XP 嵌入式版本上运行 .Net 3.5 应用程序.此应用程序通过串行 (COM) 端口写入和读取一些数据.该应用程序在我的笔记本电脑(Windows XP Professional)上运行良好，但在 Windows XP 嵌入式上运行良好.我不断收到此错误:

I am running a .Net 3.5 application on Windows XP embadded version. This application writes and reads some data over the serial (COM) port. The application works fine on my laptop (windows XP Professional) but not on windows XP embedded. I keep getting this error:

System.IO.IOException:由于线程退出或应用程序请求，I/O 操作已中止.

System.IO.IOException: The I/O operation has been aborted because of either a thread exit or an application request.

可能是什么原因造成的?

What could be the causing it?

一些附加信息:要阅读，我使用的是 ReadExisting 而不是 Readline.另外，在阅读之前，我要确保端口也已打开.

Some additional info: to read, I am using ReadExisting and not Readline. Also before reading I am making sure the port is open too.

System.IO.IOException: The I/O operation has been aborted because of either a thread exit or an application request.
at System.IO.Ports.SerialStream.EndRead(IAsyncResult asyncResult)
at System.IO.Ports.SerialStream.Read(Byte[] array, Int32 offset, Int32 count, Int32 timeout)
at System.IO.Ports.SerialStream.Read(Byte[] array, Int32 offset, Int32 count)
at System.IO.Ports.SerialPort.ReadExisting()
at ScalesApp.Scales.handleDataReceived(Object sender, SerialDataReceivedEventArgs e)
at System.IO.Ports.SerialPort.CatchReceivedEvents(Object src, SerialDataReceivedEventArgs e)
at System.IO.Ports.SerialStream.EventLoopRunner.CallReceiveEvents(Object state)
at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack)
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)

推荐答案

问题是SetCommState的DCB中启用了fAbortOnError，这解释了大部分SerialPort对象抛出的IOExceptions.一些 PC/手持设备具有默认启用错误中止标志的 UART - 因此串行端口的 init 例程必须清除它(微软忽略了这样做).SerialPort 对象在设计时并未考虑启用 fAbortOnError.

The problem is that the fAbortOnError is enabled in SetCommState's DCB, which explains for most of the IOExceptions thrown by the SerialPort object. Some PCs / handhelds have UARTs that enable the abort on error flag by default - so it's imperative that a serial port's init routine clears it (which Microsoft neglected to do). The SerialPort object wasn't designed with fAbortOnError enabled in mind.

我最近写了一篇长文来更详细地解释这一点(见这个如果你有兴趣).

I wrote a long article recently to explain this in greater detail (see this if you're interested).

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