Re: DISP and permissive record.

[Andrew Johnson <anj@aps.anl.gov>]

Hi Emmanuel,

Emmanuel Mayssat wrote:
> On Tue, 2007-03-27 at 14:10 -0500, Ned D. Arnold wrote:
>
> > A better solution might be to use Channel Access security rules such 
> > that writes to GAIN are not allowed when RUNNING.  This stops CA from 
> > writing to VAL and EDM should show you that writing is disallowed.
>
> What are you referring to here? The DISP field?

If you've never heard of Channel Access security rules I suggest you sit 
down with Chapter 8 (Access Security) of the IOC Application Developers' 
Guide sometime.  They have nothing to do with the DISP field.

> I just remembered that there is a permissive record in the record
> manual. What are the typical application for such a record?

http://www.aps.anl.gov/epics/wiki/index.php/RRM_3-13_Permissive
The Permissive record was designed to facilitate interlocked 
communication between two programs.  It has not been converted to R3.14 
to my knowledge, and I'm not aware of anyone who is actually using it. 
There have been at least a couple more recent records designed for 
vaguely similar activities such as the APS runControl record and the 
CAD/CAR/SIR records from Gemini and Observatory Sciences.

- Andrew
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