Experimental Physics and
Industrial Control System

"Davidsaver, Michael" <[email protected]> · Mon, 20 Jun 2011 11:21:20 -0400

A simple way to get different scan rates based on a binary status.  I
haven't checked that this example works, but I think it gives the basic
idea.

Record(bi, "$(P)moving") {
}

Record(fanout, "$(P)slow") {
  Field(SDIS, "$(P)moving")
  Field(DISV, "1")
  Field(SCAN, "1 second")
  Field(FLNK, "$(P):opticalscale")
}

Record(fanout, "$(P)fast") {
  Field(SDIS, "$(P)moving")
  Field(DISV, "0")
  Field(SCAN, ".1 second")
  Field(FLNK, "$(P):opticalscale")
}

Record(ai, "$(P):opticalscale") {
}

Behavior of SDIS and DISV is described here:

http://www.aps.anl.gov/epics/wiki/index.php/RRM_3-14_dbCommon

> -----Original Message-----
> From: [email protected] [mailto:tech-talk-
> [email protected]] On Behalf Of Silver
> Sent: Monday, June 20, 2011 10:42 AM
> To: tech-talk
> Subject: a puzzle about using stream device driver
> 
> hi,
> 
> I am using stream device driver to communicate a galil motion control
> which model is dmc21x3. To  get the value of optical scale, I use a ai
> record like this:
> 
> record(ai,"$(PREFIX):opticalscale")
> {
>         field (DESC, "opticalscale position")
>         field (DTYP, "stream")
>         field (INP, "@dmc2143.proto ai_opticalscale motor")
>         field (SCAN, ".5 second")
> }
> In that, I use the period scan. It works fine.
> But in most of time, the value doesn't change. That means the IOC has
> to communicate with device periodly. As the value only changes during
> the motor moving,  may I use I/O Intr mode?
> I checked the online document of stream device, seems the I/O Intr
mode
> is not suitable for this case. Is there any good ways to avoid
checking
> the devcie periodly?
> Thanks a lot for your help.
> 
> Best regards
> Geyang  2011-06-20
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System