Shutdown Cleanly with Infinite Timeout and hardware trigger

Answered

jr434343

• August 03, 2023 19:47

I have an application that uses an external hardware trigger. 

        camera->TriggerMode.SetValue(TriggerMode_Off);
        camera->TriggerSource.SetValue(TriggerSource_Line2);
        camera->TriggerActivation.SetValue(TriggerActivation_FallingEdge);
        camera->TriggerSelector.SetValue(TriggerSelector_FrameStart);
        camera->TriggerMode.SetValue(TriggerMode_On);
        camera->AcquisitionMode.SetValue(AcquisitionMode_Continuous);
        camera->TLStream.StreamBufferCountMode.SetValue(Spinnaker::StreamBufferCountModeEnum::StreamBufferCountMode_Manual);
        camera->TLStream.StreamBufferCountManual.SetValue(10);
        camera->TLStream.StreamBufferHandlingMode.SetValue(Spinnaker::StreamBufferHandlingModeEnum::StreamBufferHandlingMode_OldestFirst);

Since the time between triggers varies and will, at times, be very long, I have the timeout set to infinite.  

Acquisition is running on it's own thread in a loop: 

camera->BeginAcquisition();
// Other setup code

while(running) {
    ptrGrabResult = camera->GetNextImage(INFINITE);
    /*frame handling code*/
}

Where I am stuck is at shutting down the application cleanly...

Let's say the external trigger will not be firing for a while and the GetNextImage() call is just blocked until it does.  If I want to shutdown the application at this time, it appears I can't do much until GetNextImage returns. 

From the main thread, if I call:

camera->EndAcquisition();

It hangs until the GetNextImage call returns.

Forcing the camera's hardware trigger to fire resolves the issue, but this is not a great option for the application as it would require a hardware change in our system (a small one, but we'd prefer no change at all).

Is there a way to interrupt the call to GetNextImage when ready to shutdown?  Is there a better design for handling shutdown when there GetNextImage timeout is set to INFINITE?   

0

• Official comment

  

  TDY_Ifeanyi

  Community team

  • August 04, 2023 08:42

  

  

  Hello,

  Basically, GetNextImage is implemented such that it blocks until image arrives in the allocated buffer.

  With your application logic and program implementation, I would rather not set the timeout to infinite. 

  Instead apply any of these options:

  1. use image event approach to grab image from camera(recommended). Please reference ImageEvents example code part of spinnaker sdk on how to implement this.
  2. Set specific timeout period for each GetNextImage, and ignore any timeout exception

  I hope this approach helps to resolve this issue.

  Regards,

  Ifeanyi

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