Re: Waveforms in Archiver Appliance

[John Dobbins via Tech-talk <tech-talk at aps.anl.gov>]

In Matlab I am doing

pv = 'S7B1_VER'

start_time = '2022-04-21T13:15:00.000Z'

end_time  = '2022-04-21T13:15:10.000Z'

 urlwrite('http://archive-chess.classe.cornell.edu/retrieval/data/getData.mat', ...

         'temp.mat', 'get', ...

         {'pv',pv, 'from', start_time, 'to', end_time});

but the temp.mat file I get back is empty.

In the archiver Appliance details for this PV:

PV Name                            S7B1_VER

Instance archiving PV              appliance0

Archival params creation time:     Apr/21/2022 12:05:35 -04:00

Archival params modification time: Apr/21/2022 12:05:35 -04:00

Archiver DBR type (from typeinfo): DBR_WAVEFORM_DOUBLE

Is this a scalar:                  No

Number of elements:                50

Precision:                         0.0

Units:

Is this PV paused:                 No

Sampling method:                   MONITOR

Sampling period:                  1.0

Are we using PVAccess?            No

Extra info - SCAN:                Passive

Extra info - RTYP:                waveform

Channel Name                      S7B1_VER

Host name                         chess62.classe.cornell.edu

Controlling PV

Is engine currently archiving this?  yes

Archiver DBR type (initial)       DBR_WAVEFORM_DOUBLE

Archiver DBR type (from CA)       DBR_WAVEFORM_DOUBLE

Number of elements per event (from CA) 50

Is engine using monitors?            yes

What's the engine's sampling period? 1.0

The SCAN period (ms) after applying the jitter factor 0

Is this PV currently connected?      yes

Connection state at last connection changed event Not connected

When did we receive the last event? Apr/21/2022 13:51:48 -04:00

What did we last push the data to the short term store? Apr/21/2022 13:51:46 -04:00

When did we request CA to make a connection to this PV? Apr/21/2022 12:05:55 -04:00

When did we first establish a connection to this PV? Apr/21/2022 12:05:55 -04:00

When did we last lose and reestablish a connection to this PV? Apr/21/2022 12:21:25 -04:00

When did we last lose a connection to this PV? Never

How many times have we lost and regained the connection to this PV? 1

How many events so far? 5425

How many events lost because the timestamp is in the far future or past so far? 0

Timestamp of last event from the IOC - correct or not. Apr/21/2022 13:51:48 -04:00

Any thoughts?

John

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From: John Dobbins <john.dobbins at cornell.edu>
Sent: Thursday, April 21, 2022 12:20 PM
To: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: Re: Waveforms in Archiver Appliance

 

What is the easiest way to get this data (waveforms) out of the archiver?

John

---

From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of John Dobbins via Tech-talk <tech-talk at aps.anl.gov>
Sent: Thursday, April 21, 2022 12:14 PM
To: Michael Davidsaver <mdavidsaver at gmail.com>
Cc: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: Re: Waveforms in Archiver Appliance

 

Michael ,

It turned out to be the array size/EPICS_CA_MAX_ARRAY_BYTES.   I was only putting 50 values in the array but NELM =2048. Reducing NELM fixed the problem.

Also, thanks for the pointer to the policies info. I was wondering about that.

John

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From: Michael Davidsaver <mdavidsaver at gmail.com>
Sent: Thursday, April 21, 2022 12:07 PM
To: John Dobbins <john.dobbins at cornell.edu>
Cc: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: Re: Waveforms in Archiver Appliance

 

On 4/21/22 06:47, John Dobbins via Tech-talk wrote:
> All,
>
> Does the EPICS Archiver Appliance accept waveforms? The documentation suggests it does, but I was unable to add one (after initial sampling its status is 'not being archived').

You may be running afoul of a policy condition.

cf. the default policy.

https://github.com/slacmshankar/epicsarchiverap/blob/master/src/sitespecific/slacdev/classpathfiles/policies.py


> Thanks,
>
> John Dobbins
>
> Research Support Specialist
> Cornell High Energy Synchrotron Source
> Cornell University
>
> www.chess.cornell.edu <http://www.chess.cornell.edu>
>
>
>
>