Experimental Physics and
Industrial Control System

Stefan Heim <[email protected]> · Fri, 24 Aug 2007 09:55:08 +0200

Hello,

On Freitag, 24. August 2007, Heinrich du Toit wrote:
> This is about the best thing I saw so far for DAQ under linux:
>
> http://www.comedi.org/index.html
>
> I was wondering if anybody else has some ASYN/EPICS thing for this
> already?

I wrote a basic device support for comedi devices. Since A/D was all I needed 
(and could test) at the time, so far it supports only ai records. To sample 
channel #4 on comedi device #0 subdevice #0 and average over 1000 samples in 
one sweep, you'd have something like

record (ai, "RECNAME")
{
        field(DTYP, "comedi")
        field(INP,  "@D0 S0 C4 A1000")
}

in your database. In production use here since ~1 year.

> Else I'm interested in developing something :)
>
> Let me know what you think... also if somebody is willing to work
> together developing this. with me?

If you want I can dig up what I have and send it to you. Didn't take my time 
to cleanse the code and publish it so far. Unfortunately I won't have too 
much spare time to spend on a better comedi device support in the next few 
months.

> Also if you would be interested in using this? Would be nice to know if
> it would be used?

To make it generally useful, we'd have to add support for at least ao and 
bi/o. If we'd add a comedi record that you could use to configure (analog 
range selection, analog reference selection, calibration via internal 
dacs, ...) any comedi device from EPICS, I think it would start being used in 
linux SoftIOCs.

Hope this helps,
-Stefan

-- 
Stefan Heim, PhD Student X-ray microscopy
BESSY mbH, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
voice: +49 30 6392 3177 fax: + 49 30 6392 4757 e-mail: [email protected]
BESSY mbH - Mitglied der Leibniz Gemeinschaft
Vorsitzender des Aufsichtsrates: Prof. Dr. Dr. h.c. mult. Joachim Treusch
Geschäftsführer: Prof. Dr. Dr. h.c. Wolfgang Eberhardt, Prof. Dr. Eberhard 
Jaeschke, Sitz Berlin, AG Charlottenburg, HRB 14635

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System