PSUs: Determine whether TTi CPX400SP can be used in place of PL-P PSU Controller

[iangillingham-stfc]

Issue Description

As a electronics engineer, I would like to be able to use a TTi CPX400SP PSU in place of an existing TTi PL-P PSU.

There is a TTI CPX400SP in the electronics lab, which Ethan Baker has tested through ibex using the TTIPLP IOC and all the buttons and readouts on the device screen seem to work.
The initial request was whether the PLP IOC could/should just be copied and renamed to CPX400SP and just confirm if there is any additional functionality is being overlooked.
As these PSUs cover a good range for use on experiments and we will likely be using them more in the future.

How & Where?

Electronics lab

Reproducible (Yes/No)?

N/A

Additional Information

• At first glance, there are some significant functional differences, the CPX400SP belongs to the PowerFlex range, permitting both V and I to be adjusted on a single output, to a maximum power of around 420W, whereas the PL-P may have multiple outputs of around 90W each. I would guess that there will be use cases to be aware of and that the two command sets are likely to have differences.

I am fairly surprised that the CPX400SP is behaving as expected, using a PL-P IOC.

• There may be some use cases dictating that a 'drop-in' replacement should not be attempted.

Acceptance Criteria

_{What is the acceptance criteria of this ticket? What should the reviewer expect to be complete?}

• Determine whether the CPX400SP can be used as a 'drop-in' replacement for the PL-P, using the PL-P IOC.
• Collate functional differences, available features, constraints, etc. and discuss with electronic lab to decide how or whether to proceed.

How to Review

_{Before making a PR...}

• Documentation has been created to
  -- list the functional differences between the two PSU models
  -- conclude whether the CPX400SP can be a 'drop-in' replacement
  -- a decision documented as to how to progress (if at all)