Experimental Physics and
Industrial Control System

"Peregrine M. McGehee" <[email protected]> · Tue, 06 Aug 2002 13:37:15 -0600

Dear all,

I looking for a sense of what the present state of the art in
presenting a high-level view (i.e. non-PV) of control 
system data to the users is. This should remind you of
the early device lib, cDev, the SOSH effort, and other
developments (e.g. physics level interfaces to accelerators).

We will developing a series of Channel Archiver (libIO)
clients that will assist our users in extracting 
EPICS-based engineering data and wonder if all or part of
the required infrastructure already exists.

Specifically, even in the presence of documented and
adhered to PV naming conventions, users will ask for
either live or archived control system data in terms
familiar to them. 

For example, here at the Sloan Digital Sky Survey
a common request is for "telescope performance" data
for a spectroscopic observation defined by "modified
Julian date" (an astronomical calendar) and the 
"spectroscopic plate number".

Fulfillment of their request is a two step process, first:
the "modified Julian date" and "spectroscopic plate number"
must be mapped into a range of timestamps. Secondly,
what they mean as "telescope performance" data must be
mapped onto a set of EPICS PV names. The former is an 
internal bookkeeping issue. The latter generates a hierarchy 
of PV names:

"telescope performance" =>
	"tracking" =>
		list of PVs.
	"thermal management" =>
		"primary mirror" =>
			list of PVs.
		etc.
	etc.

Aloha,
	Peregrine
-- 
Peregrine M. McGehee	[email protected]	(505) 667-3273
Sloan Digital Sky Survey / Spallation Neutron Source
MS H820, Los Alamos National Laboratory, Los Alamos, NM 87545

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System