Re: Disable database question

["Hu, Yong" <yhu@bnl.gov>]

Another suggestion: if you want nobody could change the PV value from CA
clients (EDM, CSS, caput command, etc.), you may also consider setting the
field DISP to 1 which ignores all ca_put except the field DISP itself.
Even when the record processing is disabled by using the field SDIS,
people still can change the record value (the field VAL) from CA clients
if the field DISP is 0 (default value).

Yong

-----Original Message-----
From: Andrew Johnson <anj@aps.anl.gov>
Date: Thursday, October 30, 2014 at 1:57 PM
To: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Subject: Re: Disable database question

Hi Elmer,

On 10/30/2014 11:48 AM, Elmer Pensack wrote:
> This may sound like an odd request, but is there a way to stop
> processing all PVs in the database? I know I can stop processing
> individual PVs using  the DISV field, but I was wondering if there was a
> way to stop processing the whole database at once without looping
> through every PV.

There is an IOC command "iocPause" which pauses the IOC, stopping all
the scan threads, CA input link processing and the RSRV CA server
threads; use "iocRun" to restart everything again. However depending on
what your device and driver support do this might have deleterious
effects on them, so you should test the IOC thoroughly before relying on
this.

Device and driver support can request notification of the start and end
of a pause using the initHooks facility, and can see that the IOC is not
active by looking at the interruptAccept variable.  While the IOC is
paused new CA clients will not be able to connect to any PVs on the IOC,
and already-connected clients will disconnect after a 35 second delay.

If you want the IOC to stay alive and visible to the outside world then
Bob's suggestion of pointing all the record's SDIS links (which he
mis-spelled as DISL) to a single "ioc enable" PV would probably be
better. There is a brief description of this mechanism at
https://wiki-ext.aps.anl.gov/epics/index.php/RRM_3-14_dbCommon#Scan_Fields

HTH,

- Andrew
-- 
People everywhere confuse what they read in newspapers with news.
-- A. J. Liebling