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<== Date ==> <== Thread ==>

Subject: Re: Scaling a waveform record
From: Tim Mooney <[email protected]>
To: Tech-Talk <[email protected]>
Date: Mon, 05 Jun 2006 10:20:17 -0500
Oops, forgot to cc: tech-talk on this

-------- Original Message --------
Subject: Re: Scaling a waveform record
Date: Mon, 05 Jun 2006 09:36:28 -0500
From: Tim Mooney <[email protected]>
To: Paul Joireman <[email protected]>
References: <[email protected]>



Paul Joireman wrote:
> Hello,
>
> I am working with a VME digitizer board that writes its digitized samples to a
> block of A32 memory space on the board.  I can read these values into a
> waveform record using instrument I/O support, however, I would like to
> scale the raw values to engineering units.   What is the best way or a way
> to do this with a waveform record?

Here are some options:

1) Modify the device support software to do the conversion.  The waveform record
doesn't appear to have fields dedicated to holding values that would direct the
conversion from raw to engineering-unit values, so your device support should
also support another record type (ao, most likely), and instances of this record
could hold offset and scale values.

2) Use the array calc (aCalcout) record, a new addition to the synApps 'calc'
module (new in version 2.6). See
	http://www.aps.anl.gov/aod/bcda/synApps/calc/calc.html
In this case, offset and scale values would be scalar fields of the aCalcout
record (or simply constants in the expression).

3) Write a subroutine for the genSub record.  In this case as well, scalar
fields of the genSub record could hold offset and scale values.

I would go with option (1) if I didn't already have the calc module installed,
because installing the calc module also requires installing the sscan and
genSub modules (or modifying the calc module so it doesn't need those other
modules).

--
Tim Mooney ([email protected]) (630)252-5417
Beamline Controls & Data Acquisition Group
Advanced Photon Source, Argonne National Lab.

References:
Scaling a waveform record Paul Joireman

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