Talk:Design

From NeXus

Following the discussions with our new synchrotron chums, it occurs to us that it would be very useful to have a utility group in which we can store positioner information. We can therefore consider a simple NXposition group:

<?xml version="1.0" encoding="UTF-8"?>
<!--
URL:     http://www.nexus.anl.gov/classes/xml/NXpositioner.xml
Editor:  Nick Maliszewskyj <nickm@nist.gov>
$Id: NXpositioner.xml,v 1.2 2005/07/19 04:10:26 rio Exp $

This is a generic container for positioner information. Values
used by experimenters are to be recorded (perhaps as a vector
in the case of scans) along with information that will allow the
experimenter to back-calculate the position readable from
the motor controller or vernier. An example relationship would
be:
    position = (parity) * (vernier - offset)
where (parity) is +1/-1
-->
<NXpositioner name="positioner_name">
   <offset type="NXfloat" units="units">
       {Offset relating value stored and value 
        read from device/vernier, etc.}?
   </offset>
   <position type="NXfloat[]" units="units">
       {Value of positioner}
   </position>
   <parity type="NXfloat">
       {Parameter indicating direction of "positive" motion:
        +1 for positive, -1 for negative
   </parity>
</NXpositioner>