Experimental Physics and
Industrial Control System

Dirk Zimoch <[email protected]> · Fri, 20 Sep 2013 13:48:08 +0200

Hi Emmanuel,

I have tried EPICS on cRIO but I am not satisfied with it. I do not like

that neither alarms nor time stamps are forwarded to EPICS. LabView and

EPICS communicate through a shared memory region which contains only

values and is processed by both sides with independent cycle rates.

So when your EPICS record is scanned ".1 second", you get a new

timestamp every 100 msec. But that does not mean that LabView has

updated the value in the meantime. Not even dream of "I/O Intr"

processing whenever LabView writes a new value.

Worse is that alarms are not handled. I looked into the LabView EPICS VI

and found that in fact if it gets an error input, it skips writing into

the shared memory! That means if something goes wrong on the LabView

side (e.g broken hardware) EPICS happily reads the last good value and

updates its timestamps. In my opinion the worst way you can deal with

faults.

I reported these problems to NI a long time ago. But since they seen not

able to do anything about this, I cancelled all NI related projects.

Dirk

On 19.09.2013 22:26, Emmanuel Mayssat wrote:

All,

While investigating high-level framework for EPICS, I came across the following page
http://digital.ni.com/public.nsf/allkb/BEF3C387D96E1A0C86257A3600508278

Is any one using LabView with EPICS?
What are the benefit of such a setup?
What are the drawbacks?

Regards,
--
Emmanuel

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System