MAPS: Provide support to read pressure values from vacuum PLC

[davidkeymer]

Feature Description

As an instrument scientist, I would still like to be able to read the beamline pressures once communication with the TPG300s has been moved to a new PLC.

Explanation

Many PLCs in and around ISIS are now long obsolete and so there is a programme to upgrade them, starting with that for the MAPS vacuum system. The plan also includes the convergence on a common protocol, OPCUA, for which there is EPICS support.

This ticket will serve as a 'proof of concept' as the plan is to gradually upgrade other vacuum PLCs and read further values from them (c.f. RIKENFE vacuum system).

Additional Information

• The ISIS Electrical Controls Group have a spare OMRON PLC with which testing could be performed
• There is documentation and are examples of OPCUA usage on the GitHub site linked to above
• An additional IOC and OPI will need to be created
• No changes to the existing TPG300 IOC and OPI are required

_{See our Git Workflow.}

Acceptance Criteria

• Original beamline pressure values are available as (new) PVs
• An OPI exists to display these values
• IBEX configurations, components and blocks are edited to reflect these changes

How to Review

_{To the reviewer: Make sure to update submodules!}