Experimental Physics and
Industrial Control System

Zimoch Dirk via Tech-talk <tech-talk at aps.anl.gov> · Wed, 25 Jan 2023 08:28:10 +0000

On Tue, 2023-01-24 at 12:17 -0600, Andrew Johnson via Tech-talk wrote:
> 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.
> 

In particular, the longing record does not support floating point values, and %E
is a floating point format. If the value would actually fit into an EPICS "LONG"
(i.e a 32 bit signed integer) once converted is a secondary question.

> Changing the record into an ai should fix that.

Correct.

Dirk

> 
> - 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
> > 
>  

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System