3.3.1.43. NXpositioner

Status:

base class, extends NXobject

Description:

A generic positioner such as a motor or piezo-electric transducer.

Symbols:

No symbol table

Groups cited:

NXtransformations

Structure:

@default: (optional) NX_CHAR

Declares which child group contains a path leading ...

Declares which child group contains a path leading to a NXdata group.

It is recommended (as of NIAC2014) to use this attribute to help define the path to the default dataset to be plotted. See https://www.nexusformat.org/2014_How_to_find_default_data.html for a summary of the discussion.

name: (optional) NX_CHAR

symbolic or mnemonic name (one word)

description: (optional) NX_CHAR

description of positioner

value: (optional) NX_NUMBER (Rank: 1, Dimensions: [n]) {units=NX_ANY}

best known value of positioner - need [n] as may be scanned

raw_value: (optional) NX_NUMBER (Rank: 1, Dimensions: [n]) {units=NX_ANY}

raw value of positioner - need [n] as may be scanned

target_value: (optional) NX_NUMBER (Rank: 1, Dimensions: [n]) {units=NX_ANY}

targeted (commanded) value of positioner - need [n] as may be scanned

tolerance: (optional) NX_NUMBER (Rank: 1, Dimensions: [n]) {units=NX_ANY}

maximum allowable difference between target_value and value

soft_limit_min: (optional) NX_NUMBER {units=NX_ANY}

minimum allowed limit to set value

soft_limit_max: (optional) NX_NUMBER {units=NX_ANY}

maximum allowed limit to set value

velocity: (optional) NX_NUMBER {units=NX_ANY}

velocity of the positioner (distance moved per unit time)

acceleration_time: (optional) NX_NUMBER {units=NX_ANY}

time to ramp the velocity up to full speed

controller_record: (optional) NX_CHAR

Hardware device record, e.g. EPICS process variable, taco/tango …

depends_on: (optional) NX_CHAR

NeXus positions components by applying a set of translations and rotations ...

NeXus positions components by applying a set of translations and rotations to apply to the component starting from 0, 0, 0. The order of these operations is critical and forms what NeXus calls a dependency chain. The depends_on field defines the path to the top most operation of the dependency chain or the string “.” if located in the origin. Usually these operations are stored in a NXtransformations group. But NeXus allows them to be stored anywhere.

TRANSFORMATIONS: (optional) NXtransformations

Hypertext Anchors

List of hypertext anchors for all groups, fields, attributes, and links defined in this class.

NXDL Source:

https://github.com/nexusformat/definitions/blob/main/base_classes/NXpositioner.nxdl.xml