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

Subject: Re: Doubt regarding Process Variable
From: "Kasemir, Kay" <kasemirk@ornl.gov>
To: manta santosh aditya santosh_aditya <santosh_aditya@ecil.co.in>
Cc: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Date: Wed, 4 Apr 2012 11:33:03 -0400
Hi:

There is no central PV service.
Out of the box, nothing in EPICS gives you a list of all PVs.

It's a feature, kind of like the internet:
http://www.google.com -> You see the web page
http://www.goxxle.com -> Can't find server www.goxxle.com

caget correct_pv_name -> You see the value
caget wrong_pv_name   -> Timeout

The feature is that you do not depend on a central name server.
Nothing to set up, nothing to break.

Besides: PV names are unbounded.
Every field of every record can be a possible PV name, so the list of all
possible
names would be huge. What you want is probably a list of record names.

Eventually, most sites that use EPICS develop their own way of getting a
list of all PVs.
Or: records.

Examples:
At the end of startup, IOCs run dbl > file as Eric shows,
then something parses those files into a central database.

JLab has presented a name server based on a modified channel access gateway
that 'remembers' names and the IOCs that provide them.

IRMIS uses crawler scripts to parse IOC startup files for EPICS records
and their fields.



-Kay



From:  Eric Norum <wenorum@lbl.gov>

The 'dbl' command will print a list of record names.EPICS st.cmd startup
scripts often create a file of record names with a command something like:

dbl >"/iocinfo/pvnames/$(IOC)"

after the "iocInit" command.


On Apr 3, 2012, at 10:16 PM, manta santosh aditya santosh_aditya wrote:
How do I come to know what process variables are there in the EPICS ?
Please guide me.



References:
Re: Doubt regarding Process Variable Eric Norum

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