Add more parameter setup, fix potential PCOF issue

[FreddieAkeroyd]

Description of work

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To test

See ISISComputingGroup/IBEX#7727

Acceptance criteria

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Code Review

• A copy of the manual has been placed on the shared drive
• Pertitent information has been stored in the wiki
• Does the IOC conform to IBEX standards?
  • PV naming.
  • Disable records
  • Record simulation
  • Finishing touches
• If an OPI has been modified, does it conform to the style guidelines?
• Do the IOC and support module conform to the new build guidelines
• Have the changes been recorded appropriately in a PR for release notes?
• Is the device's flow control setting correct? For most devices flow control should be OFF.

Functional Tests

• IOC responds correctly in:
  • Devsim mode
  • Recsim mode
  • Real device, if available
• Supplementary IOCs (..._0n where n>1) run correctly
• Log files do not report undefined macros (serach for macLib: macro to find instances of macLib: macro [macro name] is undefined...

Final steps

• Update the IOC submodule in the main EPICS repo. See Git workflow page for details.
• Reviewer has merged the associated PR for the release notes

[rerpha]

do we definitely always want to set HVEL to base velocity?

[FreddieAkeroyd]

Just for background, HVEL was not previously being set at all resulting in it defaulting to VBAS which is then being explicitly set to zero, so in the end the mclennan driver was trying to set the creep speed to 0, which the controller considers invalid, so the homing (creep) speed was never actually being set. Setting it to VELOI above would get capped at 800 sps in the driver anyway (max creep speed), but i agree is probably not ideal. I will add an extra macro for HVEL in the config.