Experimental Physics and
Industrial Control System

Jörn Dreyer via Tech-talk <tech-talk at aps.anl.gov> · Wed, 25 Oct 2023 13:53:55 +0200

Hi Erico,

yes I looked at pvxs already and it would simplify my code significantly. Unfortunately I also use EPICS-QT/qeFramework in my code that does not support pvxs yet. And I do not know if I can run pva and pvxs in parallel in my IOC. I need to test that. 

Regards,

Jörn

Am Mittwoch, 25. Oktober 2023, 13:16:38 CEST schrieb Érico Nogueira Rolim:
> Hi Jörn,
> 
> Have you tried using PVXS [1]? I would expect its interface to be much
> easier to use.
> 
> Cheers,
> Érico
> 
> [1] https://github.com/mdavidsaver/pvxs
> 
> On 25/10/2023 01:35, Jörn Dreyer via Tech-talk wrote:
> > Hi Mark,
> >
> > thanks for the answer.Unfortunately I was not able to figure out how this could solve my problem.
> > This clas stakes an NTNDArray and can convert it into an NDArray (toArray). One can also put an NDArray into it, but not retrieve an NTNDArray from it
> > (fromArray). But to make use of it I firs would need to get a handle to the NTNDArray that my PvaClientChannelPtr is connected to.
> > This class has 4 functions to retrieve data (getDouble, getDoubleArray, getString and getStringArray). There is no way to retrieve an NTNDArray this way.
> > I thought that PvaClientChannel would take care of the conversion internally but that seems not to be the case. So probably I have to stick with the old NDStdArray.
> >
> > I am working on a client program that is making use of pvAccess and the qeFramework to retrieve and display data.
> >
> >
> > Am Dienstag, 24. Oktober 2023, 14:18:01 CEST schrieb Mark Rivers:
> >> Hi Jörn,
> >>
> >> You might want to take a look at the code here which converts between NDArrays and NTNDArrays.
> >>
> >> https://github.com/areaDetector/ADCore/blob/master/ADApp/ntndArrayConverterSrc/ntndArrayConverter.cpp
> >>
> >> Mark
> >>
> >> ________________________________
> >> From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Jörn Dreyer via Tech-talk <tech-talk at aps.anl.gov>
> >> Sent: Tuesday, October 24, 2023 7:04 AM
> >> To: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
> >> Subject: Strange error from pvAccess
> >>
> >> Hello,
> >>
> >> I am using pvAccess to read image data from a NDPluginPVA in areaDetector.
> >> When I do the following lines in my program:
> >>
> >> PvaClientChannelPtr channel = pva->channel((m_ImagePrefix + *imgDataPV).toStdString().c_str(), m_AccessMethod->toStdString().c_str(), 2.0);
> >> epics::pvData::shared_vector<const double> array = channel->getDoubleArray();
> >>
> >> I get an error:
> >> Error: PvaClientData::getDoubleArray() did not find a scalarArray field
> >>
> >> m_AccessMethod->toStdString().c_str() returns "pva".
> >> If I use the same code with channel access it works.
> >> Do I have to pass some special string to getDoubleArray in case of NDPluginPVA?
> >>
> >>
> >> Regards,
> >>
> >> Jörn
> >>
> >>
> >>
> >>
> >>
> >
> 
> 
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System