[Dsg-mvt] MVT with premix in hall B

[Brian Eng]

Yes, a normally off/false boolean(s) that indicates if any of the MVT detectors need gas would be what I'm looking for.

The *_INFLOW_SET PVs will work just fine for calculating the mixing flow.

Basically I'm trying to see if there is something that will handle the failure case right now, the PLC is offline, but the PVs still have numbers in them. So right now if we had gas it would be trying to flow it despite the gas not actually being required.

> On Nov 10, 2017, at 7:36 PM, Nathan Baltzell <baltzell at jlab.org> wrote:
> 
> Hello All,
> 
> These EPICS pvs suffixed by SET are the setpoints used by the PLC when it is actually flowing gas.  And the START/STOP ones are control outputs from EPICS to the PLC.  I doubt any of those should be used for trying to understand the live status of the gas flow.
> 
> The pvs suffixed by INFLOW/OUTFLOW are readbacks on measured flows.  But I suspect Brian wants a boolean status for gas flow?  The FLT (fault) column on that screen may also be useful (see attached screenshot).  Depends on what logic you want here.  Also, it’s on my todo list to add a summary PV (on ‘OR’ of all faults) and add it to the overview screen for shift workers and alarms.  If that will be useful here, I’ll do it ASAP.  Or let’s define what exactly you want from EPICS for this and we’ll make it happen.
> 
> Quentin is the PLC expert on all this and defined the PLC-EPICS communications that Wesley wrote.
> 
> Ok, that is my understanding of things.
> 
> Cheers,
> Nathan
> 
> 
> P.S.  PLC appears to be offline currently, but:
> https://hallbopi.jlab.org/webopi3.3/w?opi=CLAS12_Menu-web.opi
> click CVT->BMTGas for live readings