Experimental Physics and
Industrial Control System

Tim Mooney <[email protected]> · Fri, 13 Jul 2007 17:04:36 -0500

Stefan Heim wrote:

Tim,
On Freitag, 13. Juli 2007, you wrote:

Stefan Heim wrote:

In the streamdevice protocol file I have (among others)
getX {
        out "Joe Crds ?";
        in "Joe Crds %f %*f %*f %*f %*f %*f %*f ";
}
setX {

out "Joe AxisAbs 1 %(VAL)f";

in "Joe started";

}

[...]

I think you are *telling* the streamDevice to ignore ASLO and AOFF, by

using the

format "%(VAL)f".

That's indeed the case. It's a feature, not a bug ;-) If I use %f instead
of %(VAL)f, I get the desired ASLO/AOFF scaling with streamdevice and an ao
record.

As I read the doc, it would do what you want if you
used the

format "%f". According to streamDevice/doc/ao.html, the streamDevice

would, in this case, perform the calculation
 |OUTPUT_VALUE = (OVAL-AOFF)/ASLO
without converting to integer. (I.e., the streamDevice would grab the

required

field values, and perform the calculation independently of the record.)

Can't believe this has slipped through my attention! Stupid mistake, thank you
for getting me back on track.
On a academic basis I still wonder whether to give the responsibility to
honour ASLO/AOFF to the device support is a good idea. Aren't ASLO/AOFF
supposed to be a property of _any_ ao record, regardless what device support
it might reside on?
Thanks again,

-Stefan

Yes, and your record is using these fields to calculate a value for
RVAL. Unfortunately,

RVAL isn't useful in your application because it's integer-valued. So
streamDevice is

just doing what all device support is permitted to do, which is to use
information from

the record to craft a value that a device will be able to understand.
It would be bad if,

for example, streamDevice were to use AOFF as some kind of address, and
ASLO as a

place to store the device's serial number. That would be weird.
--
Tim Mooney ([email protected]) (630)252-5417
Beamline Controls & Data Acquisition Group (www.aps.anl.gov/aod/bcda)
Advanced Photon Source, Argonne National Lab

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System