EPICS Re: Possible Access Rights improvement?

Experimental Physics and Industrial Control System

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Subject:

Re: Possible Access Rights improvement?

From:

"Kasemir, Kay" <[email protected]>

To:

EPICS Core Talk <[email protected]>

Date:

Thu, 24 Aug 2017 15:46:04 +0000

What is the use case?

Assume I have an AI record that reads from a PLC.

So I display that as a text update field on the UI.

Would you routinely display that record as a text entry field?

-Kay

From: [email protected] <[email protected]> on behalf of Ralph Lange <[email protected]>
Sent: Thursday, August 24, 2017 3:34 AM
To: EPICS Core Talk
Subject: Possible Access Rights improvement?

Dear Core-talkers,

There is a possible request from our operations group to show VAL fields of input records as having no write access, if the device support would overwrite any value written at the next record processing.

Technically, these fields are writable.

Functionally, there are issues:

The writing client (even using put-callback) will get the new value and show the operation as having succeeded.
Other clients doing gets or creating new subscriptions (e.g. newly opened panels) will see the new value.
Existing subscriptions (e.g. archivers, gateways, already open panels) will not get an update and have no clue.
Depending on the situation (DTYP, SCAN) this inconsistent state may last a while.

What are your thoughts on this?

Thanks,

~Ralph