FIX: Setting Capture has no effect in Single Mode.

[mrakitin]

Ophyd unconditionally tries to set the capture component of the TIFF plugin of the AD to 0 in https://github.com/NSLS-II/ophyd/blob/18de9724f0d9cf78f1a0e3abe3dd8da9408b6260/ophyd/areadetector/filestore_mixins.py#L427

However, this action is not supported when the TIFF plugin is in the "Single" file write mode, so that it results in the error ERROR: capture not supported in Single mode:

This PR attempts to workaround this situation.

[codecov-io]

Codecov Report

Merging #697 into master will increase coverage by 0.07%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #697      +/-   ##
==========================================
+ Coverage   91.48%   91.56%   +0.07%     
==========================================
  Files          63       63              
  Lines       10227    10228       +1     
==========================================
+ Hits         9356     9365       +9     
+ Misses        871      863       -8

Impacted Files	Coverage Δ
ophyd/areadetector/filestore_mixins.py	80.75% <100%> (+0.08%)	⬆️
ophyd/signal.py	93.62% <0%> (+0.17%)	⬆️
ophyd/log.py	77.63% <0%> (+9.21%)	⬆️

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[danielballan]

I think this should be merged but (as discussed on private channels) it would be nice to get a clearer understanding of why Capture Mode is not applicable in Single Mode.

[klauer]

I don't have a better solution (or an answer to @danielballan's question, for that matter).

👍

[prjemian]

@MarkRivers Can you explain why Capture Mode is not applicable in Single Mode. This issue is looking at the AD TIFF plugin

[kgofron]

Is this inconsistency of TIFF settings, AD release dependent? I know that Mark has been modifying the stream/ capture functionality in recent releases.

For this specific camera:
base-7-0-1-1
ADProsilica: R2-5-6-g8a179ee
ADCore: R3-3-2
asyn: 4-33-15-g7550ea6

[MarkRivers]

I think this should be merged but (as discussed on private channels) it would be nice to get a clearer understanding of why Capture Mode is not applicable in Single Mode.

There are 3 modes, SingleMode, CaptureMode, and StreamMode. The Capture control only applies in CaptureMode and StreamMode.

Capture and Stream modes are intended for collecting multiple NDArrays into memory (Capture) or appending to single disk file (Stream). Setting Capture to 0 in Single mode really should be a warning, not an error because it does not actually do anything.

Is this inconsistency of TIFF settings, AD release dependent?

This has nothing to do with TIFF, it is in the base NDPluginFile class.

I know that Mark has been modifying the stream/ capture functionality in recent releases.

I have been discussing changing the stream/capture settings, but have not made any changes. Here is the issue I created:
areaDetector/ADCore#73

[danielballan]

That all makes sense to me. Thank you, @MarkRivers!

[danielballan]

I have changed the title of this PR as there is nothing TIFF-specific about either the problem or the fix here (which affects all file plugins).

[mrakitin]

Thanks for the clarification, @MarkRivers!