Re: Control SCAN field with ai record

[Ralph Lange via Tech-talk <tech-talk@aps.anl.gov>]

Hi Tom,

The SCAN field is an enum, i.e. a menu with a limited fixed set of choices.

As with all enum/menu fields: If you write a number to it, it will be interpreted as an index into the set of choices. If you write a string, it will be matched against the choice strings.

See the Record Reference Manual (https://epics.anl.gov/base/R7-0/4-docs/RecordReference.html) for more details and available choices.

Cheers,
~Ralph

On Wed, 19 May 2021 at 14:21, Stainer Tom via Tech-talk <tech-talk@aps.anl.gov> wrote:

Dear Epics Community,

 

I have a simple problem that I am sure has been asked before but my previous searches came up blank on tech-talk, so please forgive me if it is trivial.

 

I have a simple database, consisting of two records, as shown below. This works fine, and is one of the most elementary databases you can conceive of, however, you will notice the two commented out lines.

My desire is to have the SCAN field controlled by the “scan:ai1” PV, so I can do some *caput*s to control the scan, say to go from 0.1 second to 2 seconds.

My commented out lines obviously don’t work, but I wondered how this would be possible using the database file.

 

Does anyone have any tips on how to solve this problem? (Or please point me to previous/similar solutions.)

 

# mydb.db

-------------------------------

record(ai, "scan:ai1") {

  field(INP, ".1")

}

 

record(calcout, "scan:calc1"){

#  field(SCAN, "B second")

#  field(INPB, "scan:ai1")

  field(SCAN, ".5 second")

  field(INPA, "scan:calc1.VAL")

  field(CALC, "(A<20)?(A+1):0")

}

-------------------------------

 

Kind regards,

Tom