[dsg-hallb_rich] Update/modify RICH S1 hardware interlock system on Feb. 17 to improve reliability?

[Tyler Lemon]

Hello Valery,

In 2025, there were four times where the expansion chassis responsible for measuring RICH Sector 1's two cooling air flows, cooling buffer tank pressure, and nitrogen purge flow failed.
On all four occasions, the system could not be recovered remotely and I had to go down to the hall to resolve the problem.

This clearly indicates that the expansion chassis is a weak point in the interlock system.
DSG has therefore determined alternate measurement methods for these four parameters, allowing us to remove the expansion chassis and improve system reliability.

In brief, the changes involve:
- moving the two cooling air flows to two spare ADC channels on the system's main controller
- moving the cooling buffer tank pressure and nitrogen purge flow to a two-channel, I2C ADC board

A DSG Note posted on our group webpage<https://www.jlab.org/sites/default/files/dsg/notes/2026-02.pdf> has more details on the changes.


Would next Tuesday, February 17, 2026 be a good day to make these changes?

The work would involve updating the hardware interlock software and minor rewiring inside a de-energized interlock chassis (all work covered by existing EPASes).


Also, feel free to reply with any questions you may have.

-Tyler
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