Experimental Physics and
Industrial Control System

"Leng, Yongbin" <[email protected]> · Mon, 8 Mar 2004 12:10:28 -0500

We used both Active-X interface and Shared-memory interface in our
applications.

It looks like Active-X interface is better to share data from EPICS to
LabVIEW because LabVIEW program just sends CA requests when it needs data.
And Shared-memory interface is better to share data from LabVIEW to EPICS
because LabVIEW program just needs put data into shared memory and doesn't
wait for CA process completed.

In our applications reading back an ai record costs about 0.2~0.3ms (open,
read and disconnect), reading back a 400 points waveform record costs about
0.7~1.0ms. It's a little bit slow.
I tried to open all PVs at initialization and disconnect them before exit to
reduce time cost.
But I got some trouble when I open more than 32 waveform PVs at the same
time. The last one always was lost.

Shared-memory interface is much faster. But not all record types were
supported right now. Alos it's too complicated. User has to install and
start it from outside of LabVIEW. If we can just call some subVIs to
configure database of shared-memory IOC and initialize IOC it should be
great.

Yongbin

-----Original Message-----
From: Ned Arnold [mailto:[email protected]]
Sent: Monday, March 08, 2004 11:11 AM
To: APS tech-talk
Subject: [Fwd: LabView/EPICS]

I recently had a discussion with the Product Manager of LabView
Realtime/Embedded about possibly implementing a tightly-coupled EPICS
interface to LabView. They have heard alot about EPICS from their
customers and would like to investigate what would be involved in 
providing this capability in an integrated way.

The first question for us to answer is "what do we want?". So, I would
like to hear people's experience with the EPICS/LabView interfaces that
are currently available. I know of two major ones:

   - Active-X interfaces (for clients and server)
   - Shared-memory interface to standard EPICS records (3.14)

Please contribute your experiences, comments, ideas, wishes, etc with
these solutions or let us know of any others that have been done. For 
those of you familiar with LabView, what other 
capabilities/features/performance requirements would you like to see?

The goal would be to develop a list of requirements for the
"out-of-the-box" LabView/EPICS solution.

Please reply by March 12.

      Ned

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System