Eurotherm (modbus): find solution to scaling factors [Timebox: 4.5 days, 0.5 to review]

Tom-Willemsen commented 2 years ago

Where?

In https://github.com/ISISComputingGroup/IBEX/issues/4240 basic communications with eurotherms using modbus were implemented. However, it currently needs a large number of scaling factors to be set up for each eurotherm crate - these scaling factors are very error-prone.

Eurotherms theoretically have an IEEE modbus region which provides access to full-resolution floating-point parameters, which should not be subject to these scaling problems. However we have currently been unable to read this IEEE modbus region on our office eurotherms - either 2000 or 3000 series.

This ticket is to investigate this IEEE region in more detail:

Try updating firmware on a eurotherm, see if this helps
See if we can extract the scaling factors we need from the eurotherm itself - analysis in ticket 4240 did not find anything suitable, but re-check manual.

How?

This is a sub-ticket of https://github.com/ISISComputingGroup/IBEX/issues/4240

Acceptance criteria

[ ] We can communicate reliably with eurotherms on modbus, without needing to input large numbers of scaling factors in an error-

How to Test

verbose instructions for reviewer to test changes (Add before making a PR)

Tom-Willemsen commented 4 months ago

@FreddieAkeroyd mentioned that Alex from cryogenics has used a "mapping table" to do this on some eurotherms - this mapping table isn't documented in our usual manuals but sounds like it allows any parameter to be explicitly mapped into the floating-point modbus area.

FreddieAkeroyd commented 4 months ago

This mapping is described in the "comms table" section of the eurotherm 3504 engineering manual in our usual area

ISISComputingGroup / IBEX