Experimental Physics and
Industrial Control System

Mark Rivers via Tech-talk <[email protected]> · Wed, 18 Dec 2019 12:46:21 +0000

Hi John,

The answer to that question depends in part on how you want to use the detector, and what the maximum frame rate you will actually use.  The Eiger data can be saved in a couple of modes.

1) Eiger detector control unit directly writes HDF5 files to files to its local file system.  In this mode the EPICS IOC does not use many resources, it just tells the Eiger to start and stop acquisition, the file names to use, etc.  You do need to run some software to pull those files from the Eiger controller and save them on some other file system.

2) Eiger detector control unit sends the compressed data over a ZeroMQ socket to the EPICS IOC which then run all of the normal areaDetector plugins.  In this mode the IOC uses a lot of resources and you do need to think about how to specify that computer.

In the recent versions of ADCore and ADEiger the data from the ZeroMQ socket may not need to be decompressed on the IOC, at least not at the full frame rate.  This is because the HDF5 plugin now supports "direct chunk write", which means it can take the compressed NDArrays and write them directly to an HDF5 file that includes EPICS metadata (which HDF5 files written directly by the Eiger don't have).  The compressed NDArrays can also be sent over pvAccess to ImageJ for viewing.  If you want to run other plugins (statistics, ROIs, etc.) you do need to decompressed the ZeroMQ data, either in ADEiger, or in NDPluginCodec.  Decompressing in NDPluginCodec lets you use multiple threads for the decompression.

Modes 1 and 2 can actually be used at the same time.

Assuming you want to use Mode 2 your EPICS computer should probably have a dedicated 10 Gbit Ethernet connection to the Eiger controller and another 10 Gbit connection to your file server.  It should probably have at least 20 cores, and 64 GB of RAM for buffering.

Mark

________________________________
From: Tech-talk <[email protected]> on behalf of John Dobbins via Tech-talk <[email protected]>
Sent: Tuesday, December 17, 2019 5:13 PM
To: [email protected]
Subject: computer for EPICS with EIGER 4M

All,

We have just received a DECTRIS Eiger 4M  (4 mega-pixel x 750 Hz max rate).  This particular detector comes with a "detector control unit" but requires a separate computer to host the EPICS IOC/areaDetector.  Can someone suggest what might needed in term of memory and CPU power for this computer?

Thanks,

John Dobbins

Research Support Specialist
Cornell High Energy Synchrotron Source
Cornell University

www.chess.cornell.edu

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System