IMAQdx exposure time: when the next frame with new exposure time is ready?

[dmiftakhutdinov]

I need to perform OCR on some label. To locate the label I use high exposure time to make strong contrast between wide dark and bright areas. The label itself should be acquired with lower exposure time. I open camera, run IMAQdx Configure Grab VI, and then change the exposure time with "CameraAttributes::AcquisitionControl::ExposureTimeRaw" parameter when needed. I can put some pause to be sure the camera adopted to the new value but I'd like to have a clean solution. Unfortunately, running IMAQdx Grab2 VI with "Wait for Next Buffer" is not enough. Is there any way to determine whether the new frame uses new or old exposure time?

[BlueCheese]

This behavior is all camera-dependent. I believe recent Basler cameras include the Exposure Time as Chunk Data that is optionally added to each image (and likely other vendors have this option as well). If using one of these cameras, you can simply read properties of the image to know what exposure time it was taken with. You'd then simply throw away images until you start seeing your newly-set time.