Re: scalcout and calc yielding different results

["Mooney, Tim M. via Tech-talk" <tech-talk at aps.anl.gov>]

Hi Marko,

That's not the way you initialize the value of a scalcout-record input field.

Instead of 'field(INPB, "1e-9")', you want 'field(B, "1e-9")' and so on.

Tim Mooney (mooney at anl.gov) (630)252-5417
Beamline Controls Group (www.aps.anl.gov)
Advanced Photon Source, Argonne National Lab

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From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Marco A. Barra Montevechi Filho via Tech-talk <tech-talk at aps.anl.gov>
Sent: Tuesday, September 12, 2023 3:53 PM
To: tech-talk at aps.anl.gov <tech-talk at aps.anl.gov>
Subject: scalcout and calc yielding different results

 

Hi all. I happened to bump into an interesting problem. Im using calc and scalcout records to translate a very small current measurement into a more convenient unit of measurement.

After having trouble with the software showing the wrong measurement unit, i came to the conclusion that  for some reason, although calc and scalcout are both double types, they seem to have different precision for comparisons.

I have the following example, made to get a very small amount of current in Amps and decide to either display it in pA, nA, uA, etc.:

record(ai, "CURRENT"){}

record(calc, "CALC") {

    field(INPA, "CURRENT CP")

    field(INPB, "1e-12")

    field(INPC, "1e-9")

    field(INPD, "1e-6")

    field(INPE, "1e-3")

    field(CALC, "F:=ABS(A);F<C?1:(F<D?2:(F<E?3:4))")

    field(PREC, "4")

    field(PINI, "YES")

    field(SCAN, "Passive")

}

record(scalcout, "CURRENTSCALEDUNIT"){

field(INPA, "CURRENT CP")

field(PREC, "15")

field(INPB, "1e-9")

field(BB, "pA")

field(INPC, "1e-6")

field(CC, "nA")

field(INPD, "1e-3")

field(DD, "uA")

field(INPE, "1")

field(EE, "mA")

field(CALC, "A:=ABS(A);A<B?BB:(A<C?CC:(A<D?DD:EE))")

field(OUT, "CURRENTSCALED.EGU")

field(OOPT, "Every Time")

field(PINI, "YES")

field(SCAN, "Passive")

}

record(calc, "CURRENTSCALED"){

field(INPA, "15")

field(CALC, "A")

field(PINI, "YES")

field(SCAN, "Passive")

}

However, if you caput CURRENT 9.94e-10 you will see CURRENTSCALEDUNIT.SVAL=nA and CALC.VAL=1, meaning that for the calc record, 9.94e-10<1e-09 is True but for the scalcout this is false.

Is this expected?

Thanks,

Marco

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