RE: [External] Re: Scaling mA to A: EPICS or Phoebus?

["Leblanc, Gregory via Tech-talk" <tech-talk at aps.anl.gov>]

I knew leaving out the proto file was going to bite me!  They’re using %d, so I guess that means they’re going into rval. 

 

getCurrent {

    out "AD 0";

    in "%d";

}

setCurrent {

    out "DA 0,\$1";

}

 

I modified my records to the following:

 

record(ai, "$(P)$(R)GetCurrent") {

    field(DESC, "Read output current")

    field(DTYP, "stream")

    field(INP, "@devPCU50_300.proto getCurrent $(PORT) $(A)")

    field(SCAN, "1 second")

    # field(SCAN, "Passive")

    field(PINI, "YES")

    field(EGU, "Amps")

    field(ESLO, "0.001")

    field(LINR, "SLOPE")

}

 

record(ao, "$(P)$(R)SetCurrent") {

    field(DESC, "Write output current")

    field(DTYP, "stream")

    # field(SCAN, "1 second")

    field(SCAN, "Passive")

    field(OUT, "@devPCU50_300.proto setCurrent(%d) $(PORT) $(A)")

    field(PINI, "YES")

    field(VAL, "0")

    field(FLNK, "$(P)$(R)GetCurrent")

    field(EGU, "Amps")

    field(ESLO, "0.001")

    field(LINR, "SLOPE")

}

 

And that seems to be doing what I want (screenshot attached). 

 

I think the EGUL and EGUF fields and LINEAR for the LINR field might do the same thing, but I haven’t quite parsed the aiRecord docs yet.

 

Thanks!

     Greg

 

From: Eric Norum <ericnorum at gmail.com>
Sent: Friday, June 23, 2023 12:48 PM
To: Leblanc, Gregory <leblanc at ohio.edu>
Subject: [External] Re: Scaling mA to A: EPICS or Phoebus?

 

Use caution with links and attachments.

And,

field(LINR, “SLOPE”)

Is your protocol file reading into RVAL (%d) or VAL (%e, or f or g)?

If the former then you can use ESLO to convert the value to engineering units — which in this case would be AMPS.

field(ESLO, “0.001”)

field(EGU,  “A”)

 

On Jun 23, 2023, at 9:19 AM, Leblanc, Gregory via Tech-talk <tech-talk at aps.anl.gov> wrote:

 

These power supplies expect commands in mA, and return results in mA, so I made my Phoebus display (bob file and screenshot attached) using mA, and it works OK.  But given that these supplies have an output current of 300A, 300,000 mA looks silly and is hard to read.  Is there a preferred method of tackling this problem?  Since there are "hints" as to the units in the records, it seems like someone has probably run into this before, but I didn't find anything when I searched. Any advice greatly appreciated!
    Greg

 

— 

Eric Norum

eric at norum.ca

 

 

 

 

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