Experimental Physics and
Industrial Control System

John Dobbins <[email protected]> · Fri, 24 Feb 2012 12:22:51 -0500

Andrew,

This works for me with the following caveat. If the number of points in

the waveform becomes greater than the number of points when the MEDM

screen began execution the display does not adjust. It handles reducing

the number of points and then increasing back to the original number but

if I want to exceed the number of points that was in effect when the

screen began execution I have to switch to Edit and then back to Execute.

Is this what I should expect?

John Dobbins

On 2/21/2012 7:45 PM, Eric Norum wrote:

MEDM supports variable-length waveform plots -- set the "Count Num or Channel" to the PV holding the number of points.  I usually work around the no-monitors-on-NORD problem by forward linking my waveform records to a longin record that gets its value from the waveform NORD field -- I then set the MEDM "Count Num or Channel" to that longin record -- which does post monitors on changes.  This latter problem will be moot on arrival of 3.15, of course.

On Feb 21, 2012, at 4:36 PM, John Dobbins wrote:

Andrew,

I don't know if this matters but my waveform is actually one of the outputs of a genSub record. It has a NOVA field but I could alternately use another output as a array length indicator field.

BTW, I am also open to doing this in EDM or MEDM or ???

John Dobbins

On 2/21/2012 7:17 PM, Andrew Johnson wrote:

Hi Michael,

On 2012-02-21 Michael Davidsaver wrote:

I too have had trouble doing this.  I was able to setup a rule to set
the buffer size from the NORD field of a waveform record.  The result
was that, when the size was reduced, the start of the waveform was
removed instead of the end.  So not very useful.

Also note that the NORD field of a waveform record does not get monitors
posted on it unless there is device support that explicitly does that, so this
wouldn't necessarily work too well anyway (you could forward-link the waveform
record to a longin that reads the NORD field and use that instead though).

In 3.15 any device support will still be responsible for posting monitors if
it sets NORD, but the record and soft device support will also do it when they
set NORD.

- Andrew

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System