Hi, Michael.
Thank you for the tip about using PVA link support. I’ve created a group with some PVs and the result looks like what I was trying to achieve with NTMultiChannel.
Two questions:
1 – Is there a way to call a function every time a group processes? I’d like to create a device-support-like thing to read the fields and values of each channel and calculate things.
2 – Is there a way to pvget individual fields of a group? Something like pvget grp:name.X.
Thank you,
Márcio Paduan Donadio
Control Systems Engineer - SLAC
From:
Michael Davidsaver <mdavidsaver at gmail.com>
Date: Thursday, December 17, 2020 at 7:28 AM
To: Paduan Donadio, Marcio <marcio at slac.stanford.edu>, tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: Re: Intended use of NTMultiChannel
On 12/16/20 9:11 PM, Paduan Donadio, Marcio via Tech-talk wrote:
> I have a NTMultiChannel created using the C++ API.
Which c++ API specifically?
> I pvput to channelName passing a valid PV name. I placed a printf inside the process() method just to check if the record is processing and I can confirm it does.
>
>
>
> When I pvget I expected to see the other fields of the record populated with values from the PV in channelName. Is it intended that inside process() I write the commands to bring the data for each channel and write to the fields of the NTMultiChannel? Is
there a default “record support” that has it already implemented and I can use?
If you are referring to pvDatabaseCPP, then probably not. It is more analogous to PCAS.
You might look at the PVA link support as a way of having an IOC act as a PVA client.
https://epics-base.github.io/pva2pva/qsrv_page.html#qsrv_link
> Some data:
>
>
>
> Epics base 7.0.3
>
>
>
> $ pvget GMDTest:NTScalar
>
> GMDTest:NTScalar 0
>
>
>
> $ pvput GMDTest:NTMultiChannel 'channelName=["GMDTest:NTScalar"]'
>
> Old : epics:nt/NTMultiChannel:1.0
>
> any[] value
>
> string[] channelName []
>
> int[] severity []
>
> int[] status []
>
> string[] message []
>
> boolean[] isConnected []
>
> New : epics:nt/NTMultiChannel:1.0
>
> any[] value
>
> string[] channelName ["GMDTest:NTScalar"]
>
> int[] severity []
>
> int[] status []
>
> string[] message []
>
> boolean[] isConnected []
>
>
>
> $ pvget GMDTest:NTMultiChannel
>
> GMDTest:NTMultiChannel epics:nt/NTMultiChannel:1.0
>
> any[] value
>
> string[] channelName ["GMDTest:NTScalar"]
>
> int[] severity []
>
> int[] status []
>
> string[] message []
>
> boolean[] isConnected []
>
