Error 1074397153 Cannot Detect Recognizable Video source

Question

I'm using a single PCI1410 card to acquire images from two cameras and display those images in Labview using the Multiple Camera Acquisition.vi found on the NI website.  I'm running Windows XP, and my two cameras are Sony XC-HR70's with a resolution of 1024X768 each, running ~15FPS (total for both) thru the frame grabber.  I have one camera as a master, supplying the HD & VD synch signals for both my slave camera and the PCI1410.  Here is my problem:
      Whenever I change the light intensity for the cameras drastically (ie, abruptly shutting off the light source or blocking the camera), I get an error in Labview:  "1074397153 @ IMAQ Extract Buffer.vi.   NI-IMAQ: Cannot detect recognizable video source".  If I perform a gradual decrease in light intensity, I don't get the error.  Unfortunately, the users often need to toggle on and off my camera illuminators abruptly, so a gradual transition is not an option.
       I thought this was a MAX issue, but it is not-MAX gives no errors regardless of light intensity.
       I also tried decreasing the white level and/or increasing the black level-(per NI Knowledgebase post) all that did was decrease my image quality, error still appeared.  The error first appears in imgwaitforimaqoccurrence.vi which is inside imgsessionexaminebuffer.vi. 
If I could somehow ignore the error and insert a ~ 500mS delay and then re-attempt to acquire video lock, it would probably work.  Just not sure how to do this, or if it is the right approach.  Any ideas?

Answer 1

Hey wowens,
I was wondering if you ran just a simple grab example program, and perform the same action of shutting off the camera's light source, do you get the same error? The error you are getting means that the frame grabber is not receiving any data from the camera in the expected timeout period. There shouldn't be any reason why decreasing the light quickly should stop the camera from sending data, as the camera should still be sending some data, like all black pixels or something. I might suggest tapping the data coming in with an oscilloscope to see if the data stops when you decrease the light. If you can't do this, I might suggest altering the code so that you don't stop the loop. You could also look at the shipping example called LL Scan Multiple Channels.VI. What version of the NI-IMAQ driver are you using? I would suggest that you upgrade to the most recent if you don't have it. Other than that it sounds like you need to find out what is causing the error before you start to find a solution.
I hope this helps at least a little. Let me know if you have any questions or concerns. Thanks, and have a great day.
Regards,
DJ L.