Re: Question about length of PV names

[Ralph Lange <Ralph.Lange@bessy.de>]

It depends.

The length of the records' name fields has been discussed a lot in the 
past - after some intermediate steps it has been raised for EPICS Base 
3.14 to its current value of 61 bytes (which is 60 characters plus the 
NULL). (Any record's include file in <BASE>/include will have the 
definite answer in such cases - for any version of Base.)

Note that this is the limit of the EPICS IOC database record names. A PV 
name (e.g. for Channel Access) may be longer (else you wouldn't be able 
to address fields of a record with a 60 char name).

You are correct that other tools might have different limits. The chance 
of running against a hardcoded limit of 28 or 40 characters actually 
increases with the tool's age - EDM most probably being a safe choice. 
Luckily enough EPICS stuff is distributed as source code so you at least 
have a chance to fix things you don't like. ;-)

Good luck,
Ralph


Gavin Smith wrote:

> Hello All,
>
> What is the character limit on the length of PV names in EPICS? I have 
> seen things referring to 28 chars, 40 chars and 60 chars. Whilst I 
> have sucessfully made a record with a double alphabet name (i.e. 
> 26x2=52 chars) I am wary that other programs (such as EDM) may have 
> different limits.
>
> Thanks,
> Gavin Smith.