Experimental Physics and
Industrial Control System

[email protected] (Deb Kerstiens) · Fri, 13 Oct 95 13:46:26 MDT

Ian wrote:
> 
> I have a few problems with edd/dm.  I know that there has been talk about 
> this before, but I didn't find much in the archives.  Perhaps someone 
> could remind me.  Dm is losing contact with variables in epics 
> and the strip chart is terrible, sometimes it doesn't start, 
> if it does it doesn't last long, and sometimes it suddenly starts for a 
> brief period.  Sound familiar?  My Edd is at v 1.16 and the record 
> attached to the strip chart has the MDEL field to -1.
> 
I've asked Ian for more information to try and diagnose the problem
of dm losing contact with variables.  I thought I should respond 
globally to the strip chart question since it may be useful to others.

	From the description, it sounds as though the strip chart is only 
	changing when it gets a monitor (as would be expected from the way 
	the strip chart works.)
	Even if the .MDEL field is set to -1, the chan will still only update
	regularly if the record is processed regularly, i.e. periodic or
	processed from the FLNK of another chan that is processed regularly.
	We have used a trick before to cause updates:  create a soft chan 
	that updates periodically, but has constant value such as 0.0.
	In edd, enter this chan as the first in the strip chart.  Then enter 
	the real chan(s) in the strip char in edd as "F <channame>".  If one 
	channel actually has regular monitors and all others are "Filled", 
	the strip chart will update.  Using the extra chan is useful to
	eliminate the need to process the real data channels just to get the
	info on the strip chart. (This also avoids having all dm objects that 
	reference the real channel update unnecessarily.) 
	The plot package is the one used by the archiver.  Unfortunately, it 
	is based on the notion of "synchronous" data which is a throwback 
	from the accelerator project for which it was designed (GTA, for 
	those of you who know the EPICS history.)  The "F " prefix indicates 
	to "fill" the data for that chan , i.e. use the last data gathered for 
	that chan regardless of whether it has changed since the last point.
	As Bob stated, the plots are horrible.  It is our intent to create a 
	new plot package, but currently we have no funding to do this.

I apologize for any confusion or frustration strip charts and plots may cause 
any of you.

Deb

**********************************************************************
Deb Kerstiens		[email protected]
Phone			(505)667-3396
LANL AOT-8,MSH820	PO Box 1663, Los Alamos, NM. 87545 
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System