Experimental Physics and
Industrial Control System

Brian Tieman <[email protected]> · Wed, 04 Nov 1998 09:15:30 -0600

Hi,

Mark Rivers wrote:

> >       I want to use a frame grabber on a PC running Linux. To link such
> > a system to an EPICS world I have to write a portable channel access.
>
> You may not need to use the portable channel access server for your task, you
> may be able to simply use the channel access client.  It really depends what
> you want to do.
>
> For example, I have a CCD camera controller in a PC running Windows NT.  I
> need to take a frame with this camera and save it to the local PC disk during
> a scan which is controlled by EPICS in an IOC.  The way I do this is just to
> have a soft binary record in the IOC.  The EPICS system in the IOC sets this
> flag to 1 when it wants a CCD frame taken, and waits for the flag to go back
> to 0 before continuing.  A very simple Visual Basic task in the PC just waits
> for that flag to go to 1; when it does it calls the CCD software to take a
> frame, and once the frame is safely on disk sets the flag back to 0.  This is
> all done using channel access client rather than channel access server.
>

I agree with Mark here.  We're currently taking the same approach to control PI
CCD cameras as Mark is taking with CA client running as part of the camera control
code under Win NT.  We are, however, primarily Sun based and only have the Win NT
boxes because of these cameras.  Ideally, we'd like to control and monitor the
cameras from CA clients (IDL, labview, medm, etc...) on primarily Unix, but also
maybe the Mac.  To do this level of handshaking through a middle man VME crate is
bothersome and so we're implementing CAServer on Win NT.

I have just finished my first attempts at doing this--and it works!  I don't
pretend to understand everything, or even anything!, about the server code, but I
am able to serve various PVs from it.  This is definitly the approach we will take
for the Princeton Cameras and possibly a couple of other PC software devices as
well.

> > I would also appreciate any hint about frame grabbers plugged in PC or on
> > any other platform to find the best solution.
>

We are using PI CCD systems very similar to Mark's.  There is an ActiveX interface
if you remain on Windows.  There's also a set of DLLs with a pretty straight
forward API for writing your own code (this is the approach we're taking--we
currently have a minimally functional system which we have used to collect data.)

For another project I'm working on, we're using a Bitflow, Inc Road Runner digital
interface board for the PC.  It's not a true fram grabber, but it can interface to
various digital cameras and provides pretty remarkable frame rates.  It's a
reasonable board which comes with a lot of source code--I haven't looked to see if
there's enough to write your own driver for other OSs though.

We've also toyed with the idea of moving a Photometrics camera we have to the PC
platform.  Again, under Win NT.

Brian Tieman
SRICAT--APS

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System