Experimental Physics and Industrial Control System
|
Subject: |
Re: Naming conventions for devices and Epics records |
From: |
Andrew Johnson <[email protected]> |
Cc: |
tech talk <[email protected]> |
Date: |
Fri, 17 Nov 2006 11:27:40 -0600 |
I would also suggest that you try *really* hard to limit your record
names to the maximum recommended 28 characters. You *can* make them
longer (up to 60 characters), but until the EPICS 40 character string
length limit goes away (which means until the Channel Access protocol
gets revised and the database and all of the tools are modified to use
variable length strings) using longer names *will* end up causing you
difficulties. SNS thought they had got away with using longer names but
they found problems with long strings in the SNC/Sequencer, which I
don't think they've managed to fix.
Why is the recommended limit only 28 characters? Well if you want to
change a link field via Channel Access you only have 40 characters to
hold the complete link value, and as well as the record name the link
might need dot field name (5 chars with the standard record types) and
the flags NPP/PP/CA/CP/CPP and NMS/MS which will need another 7 chars
(you can omit the space between them if necessary, but not the one that
terminates the field name). That leaves just 28 characters for the
name, and yes I am allowed to leave the terminating \0 byte out of that
calculation.
- Andrew
--
There is considerable overlap between the intelligence of the smartest
bears and the dumbest tourists -- Yosemite National Park Ranger
- Replies:
- RE: Naming conventions for devices and Epics records Gurd, Pamela A.
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- RE: Naming conventions for devices and Epics records Strong, William Herb
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ANJ, 02 Sep 2010 |
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