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<== Date ==> <== Thread ==>

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.
References:
RE: Naming conventions for devices and Epics records Strong, William Herb

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