Re: EPICS for CompactRio

["Johannes Spinneken (EGI)" <johannes@evergreeninnovations.co>]

One other observation on using the EPICS I/O servers on the cRIO. If communication speed is of concern, I would not recommend the NI I/O server. The I/O serves are not meant to provide real time capability. At the very best, you will be able to achieve a 2-3ms data round trip efficiency, which is limited by the NI shared variable engine. In practice, you are more likely to see around 10ms data round trips between your cRIO and your other EPICS infrastructure. There is quite a lot of buffering going on, particularly in the way in which the NI engine flushes its buffers to the network. For example, small packets under 8kB will only be flushed every 10ms, unless you force the flush via this VI:

 

http://zone.ni.com/reference/en-XX/help/371361P-01/lvconcepts/sv_flush/

 

Best wishes

Johannes

 

Johannes Spinneken PhD FRSA

Principal Systems Engineer

 

Evergreen Innovations UK & USA

+1 916 266 3709 (US cell)

+44 7868 923583 (UK mobile)

www.evergreeninnovations.co

 

 

 

 

 

From: <tech-talk-bounces@aps.anl.gov> on behalf of "Paduan Donadio, Marcio" <marcio@slac.stanford.edu>
Date: Thursday, 7 June 2018 at 16:26
To: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Subject: Re: EPICS for CompactRio

 

I would recommend you not to use NI shared variables architecture. I had a problem with arrays being read as a waveform record and discovered that NI implemented NORD and NELM concepts wrongly. In fact, one of this fields does not even exist.

 

I contacted the support and the answer was something like "we never mentioned 'IOC' or 'record' concepts in our material and, so, we do not expect that our solution will work exactly as an EPICS record". The solution they gave to me was to make clear that the documentation will mention that they do not provide IOCs or records.

 

Many of the fields you would expect in an EPICS record are not present.

 

I suggest that, if you can, use the other solutions mentioned previously in this email thread.

 

Best regards,

 

Márcio Paduan Donadio

Control Systems Engineer

SLAC National Accelerator Laboratory

Advanced Instrumentation for Research Division

2575 Sand Hill Rd

Menlo Park CA 94025

Office (650) 926-5007  

---

De: tech-talk-bounces@aps.anl.gov <tech-talk-bounces@aps.anl.gov> em nome de LOTRUS Paul <paul.lotrus@cea.fr>
Enviado: quinta-feira, 7 de junho de 2018 08:52:28
Para: Diego Sanz Hernando; Hartman, Steven M.; Florian Feldbauer
Cc: tech-talk@aps.anl.gov
Assunto: RE: EPICS for CompactRio

 

You have a good presentation on NI website: http://download.ni.com/pub/branches/uk/handson_followup/epics_ral.pdf
There is no alarm on RT target. Some EPICS alarm fields are there, and you can change them with a caput, but it is not enough to make it work.

In addition, I have a LV EPICS solution that is working pretty well on cRIO-9074 (VxWorks) and not starting well on cRIO-9039 (Linux).

Best,
Paul

-----Message d'origine-----
De : tech-talk-bounces@aps.anl.gov <tech-talk-bounces@aps.anl.gov> De la part de Diego Sanz Hernando
Envoyé : jeudi 7 juin 2018 16:02
À : Hartman, Steven M. <hartmansm@ornl.gov>; Florian Feldbauer <florian@ep1.ruhr-uni-bochum.de>
Cc : tech-talk@aps.anl.gov
Objet : RE: EPICS for CompactRio

As another testimony.... I confirm that the best way, in this case, is using an intermediate real IOC, to read from NI shared variables, and have the full EPICS features in the real IOC.... about the first initialization fails, I have had similar behavior.
Regards

Diego


-----Original Message-----
From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of Hartman, Steven M.
Sent: jueves, 7 de junio de 2018 15:50
To: Florian Feldbauer <florian@ep1.ruhr-uni-bochum.de>
Cc: tech-talk@aps.anl.gov
Subject: Re: EPICS for CompactRio



> On Jun 7, 2018, at 5:18 AM, Florian Feldbauer <florian@ep1.ruhr-uni-bochum.de> wrote:
>
> I have seen, that NI provides a so called EPICS Server I/O Servers plugin which, as far as I understood, can be used on the CompactRIO system to publish shared variables as PVs to EPICS CA Clients.
>
> I’d like to know if anyone has experience using the CompactRIO with EPICS?



We are using it. It is functional but it is not a full feature CA server. We are treating it like remote I/O with CA as the field bus. We have other records on an actual IOC that take the cRIO PVs as inputs. Scaling, alarms, etc are all handled by the actual IOC and clients (display manager, alarms, archive) generally interact with the IOC PVs rather than the ones served by the cRIO. One peculiarity we have seen with the cRIO is that the first client that connects does not always get a valid response.


> Does the plugin support fields like HIHI, HHSV, ADEL, MDEL?

HIHI and HHSV: yes
ADEL and MDEL: no

--
Steven Hartman
hartmansm@ornl.gov






P Please consider the environment before printing this e-mail.

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