Experimental Physics and
Industrial Control System

"Kasemir, Kay" <[email protected]> · Fri, 1 Jun 2018 13:24:44 +0000

Hi:

>With beast, is it possible to differentiate alarm messages based on the
>severity of a PV?
No, there's not.

>For example, considering a PV of type mbbi, if the value is x and the
>severity for that value is MINOR write the message "Module 1 bypassed",
i>f the value is y and the severity for this value is MAJOR write the
>message "Module 1 in fault ". It would seem not possible considering
>that the description field is unique.
>I know that I can always do this by adding and processing specific PV
>(CALC / CALCOUT, BI / BO etc.), but I was wondering if it was possible
>to do it directly.

You bring up a good point, though, that the meaning and timing of MINOR vs. MAJOR alarms should be very different.
We've found that the initial tendency from the side of subsystem experts is often to request both, while in practice it's better to only have one.
Take a pressure reading as an example:
The subsystem expert might suggest a MINOR alarm at some pressure, and then a MAJOR alarm at a slightly higher pressure.
Idea being: If operators fail to react to the MINOR alarm, they certainly need another hint to finally get going by issuing a MAJOR alarm.
In practice, this is not helpful.
As the pressure rises, operators get the MINOR alarm and start to look into the problem.
If there's now a MAJOR alarm 5 minutes later, this is not helpful.
Operators are already working on the issue, they're aware of the elevated pressure.
Another alarm for the same issue might just make operators to ignore alarms from now on because they're perceived as not adding any value.

So while configuring HIGH/HSV and HIHI/HHSV at the same time is easy, in practice this is only helpful if these represent very different responses _and_ there's a certain expected time delay between them.
If both are likely to happen within 5 minutes and the response to either is "Look at the vacuum system, try to figure out what's wrong", then pick just one pressure level and one alarm.
On the other hand, if the MINOR alarm means "Turn on another pump to reduce the pressure, but keep operating", and a further pressure rise to a MAJOR limit would take at least an hour, with the response being a very different "Open all release valves, stop operating", then configuring both alarm levels makes sense.
The different response would be spelled out in the guidance:
"This alarm indicates elevated pressure.
Note that the response depends on the level:
For a MINOR alarm, turn on another pump ...
For a MAJOR alarm, ...
"

Right now there's no way to configure different messages for the alarm levels because in practice different alarm levels for the same PV are extremely rare.
In the few cases where they're useful, the information can be placed in the guidance, or as you mention separate alarm trigger PVs can be used.

Thanks,
Kay

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System