Experimental Physics and
Industrial Control System

"Bob Dalesio" <[email protected]> · Mon, 03 Mar 2003 13:35:23 -0700

I would put it into the device support initialization area
-

It can be done at initiallization.
Device support has a pointer to the record - so it's able
to write directly into the fields ZNAM, ONAM, etc.... 
At initialization, there should be no channel access
clients connected that could request these strings before
they are initialized.
A problem would be if the assignment of these values can
change. Channel access clients monitor the value as a
short and only send the string assignments at connection
time. So that is a possible problem. If they can change -
you may want to map them from a static assigment to the
dynamic values in the device support only - and not export
the fact that the strings are assigned different values at
different times.

On Mon, 03 Mar 2003 15:29:32 -0500
 "Hoff, Lawrence" <[email protected]> wrote:

 EPICS philosophical question of the day........
 Suppose there is a piece of equipment which can be put
into

one of several modes of operation. Suppose also that the
set of possible

modes depends on the hardware configuration of the
equipment. Suppose

finally that the set of possible modes can be queried
programmatically.
 What is the "best" way to populate the "ZRST", "ONST",
...

fields of the record?
	Query the device during the "record init" phase, and
programmatically fill in the fields?
 Edit the .db file to conform to the known H/W
configuration,

and re-edit as needed if the H/W changes?
 Other?
 What are pros and cons of various approaches.
 One example of such H/W are certain frame grabbers which
have

H/W image processing built onto daughter cards. There are
different

sets of image processing algorithms available with
different daughter

cards attached.
 Another example is a transient recorder with options for

stored waveform length, which are ultimately constrained
by the amount

of memory installed.
-- Larry

Bob Dalesio
[email protected]
410 557 0297 Maryland
505 667 3414 Los Alamos
505 699 1632 Cell Phone
505 667 6087 Our Secretary (Lisa Marie)

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System