Experimental Physics and
Industrial Control System

"Allison, Stephanie" <[email protected]> · Tue, 9 Mar 2004 08:36:31 -0800

Hello -

Attached is a response from Alan Fisher at SLAC on LabView/EPICS.

Stephanie Allison
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Ned,

I have been using the Los Alamos Active-X interface for Channel Access puts and gets, as part of a system to image the electron and positron beams of PEP-II with visible synchrotron light and with visible light interferometry.

We had no video digitizer with adequate resolution for the interference fringes, but an ordinary PCI frame grabber can easily do the job. However, I did not want to write the entire interface from scratch, since there are commercial products that do much--not all, but much--of what I wanted, mostly for profiling laser beams. The catch is that most of this software comes in one of two forms: either a library of useful routines that leave you to connect them all in an overall program, or a full program with no way to modify it to add my special requirements, such as interference fringes and export of the results. Then I found a LabView program that had most of the features and sold the source code too, with no restrictions on my cusomization.

But we had to get the final results into EPICS so that we could correlate data with the rest of the machine's controls and diagnostics. The Active-X interface certainly works, and the fact that and interface to EPICS was available was the clincher in my decision to build on this commercial LabView application in the first place.

The program now runs on 3 PCs, two with frame grabbers out at the ring and one in the control room, receiving the images via the DataSocket protocol in LabView, and doing all the calculations and the user interface.

What more do I want it to do? The existing routines are fairly easy to use and get the job done, and so this part never needed much effort. I have heard from the author (Kay Kasemir) that there are limits to how many channels I can serve, but this has not yet caused me any trouble. I do have some minor gripes about transferring data that is not in simple floating-point numbers: I have never been able to read the EPICS date and time, for example, but then again I haven't needed it enough to work at that issue.

I'd like to see other user's comments. Perhaps this will start a healthy exchange.

Alan Fisher
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Dr. Alan Fisher
Physicist
Accelerator Department
Stanford Linear Accelerator Center
Mail Stop 18
2575 Sand Hill Road
Menlo Park, CA 94025
Phone: 650-926-2436
Fax:   650-926-8533
Pager: 650-846-9629
[email protected]
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System