Upgrade the EBV with BPM counters
Problem:
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people want to use a beamviewer with a camera exposure different of the count_time of a scan.
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they usually setup the camera (exposure, roi, flip, rot) outisde of Bliss and don't want this to be overwritten when doing a scan.
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most of the time, on bliss side, they don't want/need the image but only the bpm measurements
Today to perform the BPM measurements they put the Lima_ebv in a scan and therefore Bliss pushes the Lima_ebv config and overwrites what people have setup outside of Bliss. In particular the Lima_ebv exposure_time is set to count_time!
Solution:
- Use the EBV class to count on the BPM of a lima camera used as a BeamViewer.
- The address of the Lima/Bpm Tango device will be added to the EBV config
The EBV will have new 'bpm' sampling counters that starts the exposure of the associated camera and obtain the bpm values from the tango device.
The exposure time of the camera will stay as it is on the server side.
Putting the EBV in a scan will not modify the associated lima camera expo_time.
It will sample the BPM measurements as long as n*cam.expotime < count_time