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Subject: Re: SIML type CA and PINI=YES issue
From: Ralph Lange <ralph.lange@gmx.de>
To: EPICS Core Talk <core-talk@aps.anl.gov>
Date: Wed, 29 Nov 2017 21:44:07 +0100
Hi Andrew,

On Wed, Nov 29, 2017 at 9:26 PM, Andrew Johnson <anj@aps.anl.gov> wrote:
On 11/29/2017 01:13 PM, Kasemir, Kay wrote:
>> That's where out-of-band management would jump in...
> Printing a message on the IOC console would be a bit like out-of-band notification,
> but you would not see at all that via a CA client,
> while on the console you might then see that every time the record processes.

The error message should be logged too [...]
For records that might process frequently the messages would be annoying
noisy though, and when your SIML target really does live on a remote IOC
which goes down that could be a problem.

I was considering printing a message, but with our PINI-processed PLC-connected records this would mean >10K error messages at every boot.
More than annoying.

This is one of those situations when a link type that atomically reads a
dbState value might be worthwhile, and a better solution than using CA
links. Actually why limit ourselves to just binary values, why not
create a link type that provides atomic access to any shared storage
(similar to the old global symbol support, but with proper thread
protection)?

We have a single simulation switch bo record per PLC, and it resides on the IOC connecting to the PLC.
We only need CA links in SIML to not have all >10K records be in a single lock set.

>> What about setting STAT to LINK without setting the severity?
> Yes, good compromise between showing nothing and stopping the normal operation.

I didn't know you could actually do that, but it looks like you can.
[...] However those values will get copied from NSTA & NSEV into STAT & SEVR fields by
recGblResetAlarms() unconditionally, which will post a DBE_VALUE event
on both STAT and the VAL field when STAT changes even if SEVR doesn't or
is zero.
Not sure that the current GUI tools will ever actually display the
result, but maybe that doesn't matter?

I would say this is acceptable as poor man's out-of-band management.
It allows clients to check or watch this and will appear in the mouse-over bubble type GUI things.

I will prepare a merge proposal tomorrow.

Cheers,
~Ralph


Replies:
Re: SIML type CA and PINI=YES issue Andrew Johnson
References:
SIML type CA and PINI=YES issue Ralph Lange
Re: SIML type CA and PINI=YES issue Ralph Lange
Re: SIML type CA and PINI=YES issue Kasemir, Kay
Re: SIML type CA and PINI=YES issue Ralph Lange
Re: SIML type CA and PINI=YES issue Kasemir, Kay
Re: SIML type CA and PINI=YES issue Andrew Johnson

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