BeginRead does not abort IO after IOTimout has expired.

[ScottPageUSMC]

After starting an asynchronous IO operation, like BeginRead, the delegate does not return (or does not abort) after the IOTimeout period has elapsed.  I made an attempt using a System.Timers.Timer object and set its Interval through a Select...Case method based on the current IOTimeout setting.  After the timer elapsed, if the Async IO was completed then I called Device.AbortAsyncronousIO.  That cause large hang times in my app.

Is there a way to be notified of Async IO timeouts or is there a way to set a timeout period for Async IO operations?

[ScottieB]

If you haven't already seen it, the example in C:\Program Files\National Instruments\MeasurementStudioVS2003\DotNET\Examples\GPIB\SimpleAsynchronousReadWrite\CS

 would probably be helpful to you.  It shows how to use these Asynchronous calls and callbacks and successfully returns a timeout condition for me.

Scott B.

GPIB Software

[ScottPageUSMC]

Most likely, the delegate never returns because an exeption was thrown (within a Try...Catch block or not) inside of the method called by the BeginRead method.  Delegates ALWAYS terminate when an exception is thrown, even if you catch the exception inside of a Try...Catch block.  That is what most of the hang-ups I experience are caused by.  Using a thread will allow you to catch exceptions and get a response if coded correctly.

Hope this helps