Experimental Physics and
Industrial Control System

Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> · Tue, 10 Oct 2023 17:17:17 +0000

Hi Jörn,

I am curious whether you might use NDPluginPva for sending the data via a stream over the network?  That is a common thing to do.

NDPluginFile does not currently have a mechanism for continuous streaming.  A common workaround is to set NumCapture to a very large number, but that will eventually fail if the number of frames streamed is >2^31.

From a quick look at the NDPluginFile code it seems that we could change the logic so that if NumCapture is 0 it will stream forever.  It would require changes in the following lines so that the comparison with numCapture is only done if it is non-zero.

https://github.com/areaDetector/ADCore/blob/076bd4543827798537fa486c00e334722e9889f4/ADApp/pluginSrc/NDPluginFile.cpp#L743
https://github.com/areaDetector/ADCore/blob/076bd4543827798537fa486c00e334722e9889f4/ADApp/pluginSrc/NDPluginFile.cpp#L750
https://github.com/areaDetector/ADCore/blob/076bd4543827798537fa486c00e334722e9889f4/ADApp/pluginSrc/NDPluginFile.cpp#L767

I think that would be backwards compatible because NumCapture=0 currently does not do anything useful.  If the user sets NumCapture=0 that might cause existing plugins to fail.  But there is nothing preventing users from doing that now, e.g. the NumCapture record does not set DRVL=1.

If you want to test this and issue a Pull Request I'll be happy to look at it.

Mark

-----Original Message-----
From: Tech-talk <tech-talk-bounces at aps.anl.gov> On Behalf Of Jörn Dreyer via Tech-talk
Sent: Tuesday, October 10, 2023 4:49 AM
To: tech-talk at aps.anl.gov
Subject: Question regarding ADPluginFile driver

Hi,

I am currently developing an ADPluginFile driver that will  send the data via a stream over the network to a remote process for fast analysis. It can also store the data locally in various formats.
For the network transfer I would like to be able to do continuous streaming without automatic limit by a defined number of events.
Is that possible? Or can it be implemented within my code?

Regards,

Jörn

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System