RE: Waveform Records

["David Dudley" <DavidDu@cctexas.com>]

Maybe a little background would help.
I've got a PV where they want to watch real-time historical information
over the past 4 hours.

The PLC that acquires that PV stores this information in a FIFO buffer
once every 60 seconds, with time stamp information should I require it
(the PLC actually has a buffer that stores the last 48 hours, which
means I actually have 2880 samples, all available at any time).  The
desire is to 'see' that information in graphical form if possible, or in
a table form if not.

David

>>> "Dalesio, Leo" <dalesio@bnl.gov> 9/4/2008 1:14:45 PM >>>

Some issues ---
1) waveforms are just arrays. You're device support can fill it any way
you like.
2) there is a circular buffer record that already does this either ring
buffer - or successive averaging or keep high or low for each sample.
3) we do not queue the array - so if your client is not getting them
fast enough in monitoring - then you will loose old arrays. You may even
get half of one and half of another. This system needs to be set up
carefully.
4) There is a subarray record for just reading an area of interest.
5) we did not do the meta data correctly - so no indication of the unit
of time between samples within the array.


-----Original Message-----
From: tech-talk-bounces@aps.anl.gov on behalf of David Dudley
Sent: Thu 9/4/2008 2:04 PM
To: tech-talk@aps.anl.gov 
Subject: Waveform Records
 
Need a little 'training' on waveform records....

1. With a waveform record, with each scan of the I/O device, does the
device read in a single sample, or a whole waveform?

2. Can waveforms be setup to operate in a continuous FIFO manner?  In
other words, a sliding window of data items collected over time?

3. Can 'edm' display a waveform record, and if so, how?  If 'edm'
can't
display them, is there a program that can?

David

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