Add units to StandardDetector driver acquire time signal

bluesky / ophyd-async

Hardware abstraction for bluesky written using asyncio

https://blueskyproject.io/ophyd-async

BSD 3-Clause "New" or "Revised" License

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Add units to StandardDetector driver acquire time signal #426

Open DiamondJoseph opened 6 days ago

DiamondJoseph commented 6 days ago

Presumably this is part of the areadetector implementation?

Acquire time could be measured in seconds, milliseconds etc. and knowing which is crucial.

coretl commented 6 days ago

You are correct, there are no units there: https://github.com/areaDetector/ADCore/blob/1a9135976b4bc75bfdfe1ed7516a3e7d29e08e6b/ADApp/Db/ADBase.template#L173-L207

However changing these would break all our screens which do not leave space for a units field!

They are always seconds at the moment...

jwlodek commented 6 days ago

Maybe we can add a kwarg that is basically acquire time scale factor, defaulting to 1. Then we assume that the input is always in seconds, and the scale factor can adjust the number based on the device needs if for whatever reason it is not one.

DiamondJoseph commented 6 days ago

I'd prefer it to just be handled in the existing standard way, how viable is changing our screens?

coretl commented 5 days ago

I'd prefer it to just be handled in the existing standard way, how viable is changing our screens?

3 year time scales...

We could put a workaround in ophyd-async that overrides the EGU in an EpicsSignalBackend until then?

DiamondJoseph commented 4 days ago

So long as it ends up passed through the signal metadata

coretl commented 3 days ago

This needs:

epics_signal_r, epics_signal_rw, epics_signal_rw_rbv to take optional units and precision like soft_signal_rw: https://github.com/bluesky/ophyd-async/blob/8a18c3bc39a2d5f85daf5c1951447d076ec8be6d/src/ophyd_async/core/signal.py#L295-L309
Add optional metadata to CaSignalBackend and PvaSignalBackend __init__, and pass them through to converter.get_datakey like SoftSignalBackend: https://github.com/bluesky/ophyd-async/blob/8a18c3bc39a2d5f85daf5c1951447d076ec8be6d/src/ophyd_async/core/soft_signal_backend.py#L185-L186
Make the converters use the given metadata if not given by the underlying control system
Pass units="s" to acquire_period and acquire_time: https://github.com/bluesky/ophyd-async/blob/8a18c3bc39a2d5f85daf5c1951447d076ec8be6d/src/ophyd_async/epics/areadetector/drivers/ad_base.py#L47-L48