RE: [External] Re: Keysight 34980A SCPI StreamDevice

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

All right, now for the next hurdle.  I’ve got the raw data being pulled from the device, but I need to do some manipulation on it to get it into something that humans can consume.

 

I’ve got a record that looks like this:

 

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

  field(DESC, "Alphatross Vacuum Level)")

  field(DTYP, "stream")

  field(INP, "@devswag6.proto getVoltageDC(10,0.1,5012) $(PORT) $(A)")

  field(PINI, "YES")

}

 

Which I can then query with:

$ caget swag6testgetVacuumLevel

swag6testgetVacuumLevel        2.7718

 

Now, the real vacuum level is 10^(swag6testgetVacuumLevel – 10). 

Can I do that directly in this database record, or do I need to add a separate calc record? 

 

I’ve started to read through https://docs.epics-controls.org/en/latest/guides/EPICS_Process_Database_Concepts.html#linear-conversions but it’s taking more brainpower than I have available this evening. 

     Greg

 

From: Andrew Johnson <anj at anl.gov>
Sent: Tuesday, January 24, 2023 1:18 PM
To: Leblanc, Gregory <leblanc at ohio.edu>; tech-talk at aps.anl.gov
Subject: [External] Re: Keysight 34980A SCPI StreamDevice

 

Use caution with links and attachments.

Hi Greg,

I'm not a StreamDevice expert at all, but it seems to me that your design is expecting the number 9.9e37 to fit into a longin record's VAL field. In EPICS the word "long" was set in the days when an int was only 16 bits wide, so a DBF_LONG is only an epicsInt32 with a maximum value of 2,147,483,648 ~ 2.15e9.

Changing the record into an ai should fix that.

- Andrew

On 1/24/23 11:59 AM, Leblanc, Gregory via Tech-talk wrote:

Hi again,

Still trying to run down some more details about talking to these lovely Keysight boxes via EPICS.  I've got the stock SCPI stuff working, so next I wanted to read some resistance values.  I added this to my protocol file: 

getResistance {

    out "measure:resistance? \$1,\$2,\$3";

    in "%E";

}

And added this to my .db file:

record(longin, "$(P)$(R)GetIG")

{

    field(DESC, "Get Alphatross Ion Gauge Value")

    field(DTYP, "stream")

    field(INP,  "@devswag6.proto getResistance(10,0.1,(@5012)) $(PORT) $(A)")

}

After starting the ioc, I can do ' dbtr swag6testGetIG`, which sends the correct string, and gets a reply from the mainframe.  What I'm stuck on is handing the reply.  The box replies with:

 +9.90000000E+37\n

But the way I have things configured I get:

2023/01/24 12:49:07.000698 LAN0 swag6testGetIG: Format "%E" has data type double which is not supported by "swag6testGetIG".

It seems like that should work, based on: https://paulscherrerinstitute.github.io/StreamDevice/formats.html  

I don't know if I managed to compile StreamDevice with some missing library, or if I've done something else wrong along the way.  

Thanks for any pointers,

     Greg

--

Gregory Leblanc

Accelerator Engineer

Edwards Accelerator Lab - Ohio University

123 University Terrace

Athens, OH 45701 USA

leblanc at ohio.edu

M: (401) 52-OUAL1 or (401) 526-8251

-- 

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