Mapping customised pva structures to epics v4 Normative Types and v3 PVs (channel access).

[Heinz Junkes via Tech-talk <tech-talk@aps.anl.gov>]

Guten Morgen,

One thing that has been on my mind for a long time:

We have developed our own devices such as llrf generators, pulse generators, etc., which run on a Raspberry Pi or BeagleBone Black as a management interface.
We then use p4p on that devices and offer the data points in a pva structure tailored to the respective device.

E.g.

(base) hactar:~ junkes$ pvinfo  FHIFEL:llpg_1
FHIFEL:llpg_1
Server: 141.14.134.173:5075
Type:
    structure
        ushort Ch1_Width
        ushort Ch2_Width
        ushort Ch1_Delay
        ushort Ch2_Delay
        ushort Ch1_ExtraDly
        ushort Ch2_ExtraDly
        ushort Ch1_Atten
        ushort Ch2_Atten


epics@felpvagate:~$ pvinfo FHIFEL:bbamp_1
FHIFEL:bbamp_1
Server: 10.0.0.110:5075
Type:
    structure
        boolean ITLK
        boolean TRIG
        boolean PWR
        boolean STAT
        double SWR
        double FWD
        double REV
        byte RFIN
        double TSET
        double TMEAS
        int PIDI
        int PIDV
        boolean TTHI
        boolean PIDLU
        double PID_PWR
        boolean CLRER

Now we are experiencing some issues with it.

1.) The ArchiverAppliance cannot archive these PVs.
2.) Our 'old' Save&Restore supports channel access only.

How should we best deal with this?

My current idea is to implement a service (Python?) that reads this user-defined structure with pva, breaks down the structure into individual NT-pvs and offers these 'individually' via pva (for the Archiver Appliance, for example) and, at the same time, also offers these PVs as ca-PVs for channel access (for our Save&Restore).

Now the question to the group: Is there a better way? And how would you implement my idea?

Danke Heinz

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Fritz-Haber-Institut    | Phone:         (+49 30) 8413-4270
Heinz Junkes             | Fax (G3+G4):   (+49 30) 8413-5900
Faradayweg 4-6        | VC: https://zoom.fhi.berlin/junkes
D - 14195 Berlin        | E-Mail:        junkes@fhi-berlin.mpg.de
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“Sorry I’m a bit late, had a terrible time…
All sort of things cropping up at the last moment. Uh, how are we for time?”
—Zarquon's address to Milliways

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