Re: Strange error from pvAccess

[Érico Nogueira Rolim via Tech-talk <tech-talk at aps.anl.gov>]

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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