Experimental Physics and
Industrial Control System

Dirk Zimoch <[email protected]> · Mon, 20 Jun 2011 17:42:49 +0200

Geyang,

You probably want to disable scanning completely when the motor is not

moving, not just reduce the rate.

From the position-set record FLNK to a seq or similar that sets moving

to 1. Your position-read record can use the 'field(SDIS, "$(P)moving")'

and 'field(DISV, "0")' directly to process only when moving is 1. The

same for all other records that should only poll when moving.

If the device can be asked for "done" use this information to set moving

back to 0 and all polling stops. This record should as well poll only

when moving. If the device cannot be asked for "done", use a calcout

record to calculate "done" yourself.

"I/O Intr" only works if the device is sending status updates

automatically while moving, without being polled.

Dirk

Davidsaver, Michael wrote:

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