Experimental Physics and
Industrial Control System

Christian Pauly via Tech-talk <tech-talk at aps.anl.gov> · Fri, 14 Aug 2020 10:16:45 +0200

Hej Folks

Again i am facing the problem to call an external program (to read out a

sensor), but this time i would like to get the stdout output from this

program (the sensor value) into a record.

I am trying to use the ExecuteDevice module for this, and basically it

works. Here is what i do:

record(bo,      "$(P)$(R)AirFlowRun")
{
  field(SCAN,   "1 second")
  field(DTYP,   "execute")
  field(OUT,    "@ReadFlow run")
  field(FLNK,   "$(P)$(R)AirFlowStr")
}

record(stringin, "$(P)$(R)AirFlowStr")
{
  field(DESC,   "Measured Air Flow as String")
  field(DTYP,   "execute")
  field(INP,    "@ReadFlow stdout")
  field(FLNK,   "$(P)$(R)AirFlow")
}

record(scalcout, "$(P)$(R)AirFlow")
{
  field(INAA,   "$(P)$(R)AirFlowStr.VAL")
  field(CALC,   "AA")
}

The first record executes the external program, and once done it

forwards to the second record to readout the stdout output. So far it works.

Problem: The second record has to be a stringin record, so i have the

output only as string not as number. record type ai is not supported by

the EcecuteDevice module.

In order to convert the string into a usable number i am trying to use

the third "scalcout" record. It should retrieve the string via input

link, and simply convert it to a float number.

However: Specifying the input link "INAA" does not work, i get an error

"2020/08/14 10:03:51.229277 _main_ CBM:Lauda:AirFlow: Wrong I/O link

type CONSTANT"

Acording to the scalcout documentation, it should be possible to use a

link as input, so i dont get why this is not working...

Or is there an even simpler way to achieve the goal ?

As always: Any help or suggestionis very welcome !!

Best regards,
Christian

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System