EPICS Re: Accessing Elements of a Waveform Record

Experimental Physics and Industrial Control System

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

Subject:	Re: Accessing Elements of a Waveform Record
From:	"Johnson, Andrew N. via Tech-talk" <[email protected]>
To:	"[email protected]" <[email protected]>
Date:	Tue, 2 Jul 2019 21:28:05 +0000

Hi Chris,

On 7/2/19 3:43 PM, Christopher Herrmann via Tech-talk wrote:

Currently, I have a waveform record that holds 10 different values.

I was wondering if there was any way to reference an individual element

in that waveform record.

What version of Base are you running, and what is actually trying to access the element (CA client, another record, etc)?

My best solution so far is to use the "aCalcOut"

record and have it process, then output, a single hard coded value.

Something like this for the "calc" field:

field(CALC, "AA[0,0]") or field(CALC, "AA[1,1]")

While this is fine for a few elements, I may need to be able to access up

to 30 different values in a single waveform record individually.

Are there any clever or streamline ways to go about this?

If you're running Base-3.15.x or later there is (through Channel Access or a CA link), take a look at the array server-side filter which is documented here.

You could also look at the subArray record, which extracts parts of an array at a specific length and offset. This comes with all Base versions.

HTH,

- Andrew

-- 
Complexity comes for free, Simplicity you have to work for.

References:: Accessing Elements of a Waveform Record Christopher Herrmann via Tech-talk

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