Experimental Physics and
Industrial Control System

Jörn Dreyer via Tech-talk <tech-talk at aps.anl.gov> · Wed, 19 Jun 2024 14:14:04 +0200

Hi all,,

after some more investigation it turned out the the problem was an not handled error situation in which the PV did not return a valid array.
This now leaves me with the question how the data is organized in the case of the Pva plugin versus the standard NDArray data.
Where can I find some detailed information about that?

Regards

Jörn

Am Montag, 17. Juni 2024, 13:39:50 MESZ schrieb Jörn Dreyer via Tech-talk:
> Hi all,
> 
> I have a problem with EPICS 7.0.8 when trying to retrieve image data from an areaDetector using the pva protocol.
> I'm using the Pva plugin because of the size of the image (61 Mpixels). The PV is "cam:Pva1:Image" and in my program
> using pvAccess I get the following error:
> 
> Error: PvaClientData::getDoubleArray() did not find a scalarArray field
> 
> When doing the following:
> 
> pva = PvaClient::get("pva ca");
> PvaClientChannelPtr channel = pva->channel("cam:Pva1:Image", "pva", 2.0);
> epics::pvData::shared_vector<const double> array = channel->getDoubleArray();
> 
> Enabling debugging for pva gives the following:
> 
> PvaClientChannel::PvaClientChannel channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientChannel::connect channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientChannel::issueConnect channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientChannel::issueConnect calling provider->createChannel
> PvaClientChannel::channelCreated channelName WIZZLERHD:HZDR:asicam1:Pva1:Image connectState 1 isConnected false status.isOK true
> PvaClientChannel::waitConnect channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
>  PvaClientChannel::channelStateChange  channelName WIZZLERHD:HZDR:asicam1:Pva1:Image CONNECTED
> PvaClientGet::create(pvaClient,channelName,pvRequest)
>  channelName WIZZLERHD:HZDR:asicam1:Pva1:Image pvRequest structure 
>     structure field
>         structure value
> 
> PvaClientGet::PvaClientGet channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientGet::connect channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientGet::issueConnect channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientGet::waitConnect channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientGet::channelGetConnect channelName WIZZLERHD:HZDR:asicam1:Pva1:Image status.isOK true
> PvaClientGetData::create
> PvaClientGet::get channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientGet::issueGet channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientGet::waitGet channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientGet::getDone channelName WIZZLERHD:HZDR:asicam1:Pva1:Image status.isOK true
> PvaClientData::setData
> PvaClientGet::getData  channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientGet::checkConnectState channelName WIZZLERHD:HZDR:asicam1:Pva1:Image
> PvaClientData::getDoubleArray
> PvaClientData::getSinglePVField
> Error: PvaClientData::getDoubleArray() did not find a scalarArray field
> 
> The array vaiable is 0 in this case.
> No clue what I am doing wrong here?
> 
> I can retrieve the value of the pv with pvget. So it exists and is correctly filled.
> Any help appreciated!
> 
> Regards
> 
> Jörn
> 
> 
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System