Observation

Definition: abstract entity that provides telemetry data for a DataItem at a point in time.

Version Info

Introduced	Deprecated	Updated
1.0

Documentation

Description

Note: See Section Observations Schema Diagrams for XML schema. The XML schema also shows differences in XML representation of certain MTConnect entities.

Figure DeviceStream Example shows a complete example of DeviceStream for the Device shown in Device Information Model.

Note: See devicestream-example for the XML representation of the same example.

This section provides semantic information for the Observation model.

Note: See Section Observations Schema Diagrams for XML schema of Observation types.

Observations made for DataItem

Component observesact of measuring or determining the value of a property at a point in time. DataItem entities and creates Observation entities for the DataItem entities. See Figure Observations.

Observation entities made by a Component are organized by a ComponentStream which is specifically created for that Component.

Note: See Section Observations made for DataItem Example for how XML representation of the same example is separated into MTConnectDevices Response Documentresponse document published by an MTConnect Agent in response to a probe request. and MTConnectStreams Response Documentresponse document published by an MTConnect Agent in response to a current request or a sample request..

Figure Observations made for DataItem Example is a subset of Figure DeviceStream Example. It shows an example of the association between a DataItem Event type (EMERGENCY_STOP) and an Observation Event type (EmergencyStop). See Section Naming Convention for Observation types.

Figure Observations made for DataItem Example also shows example of the association between a Component type (Controller) and related ComponentStream.

Naming Convention for Observation types

The name of an Observation type MUST derive from the associated DataItem::type converted to Pascal-Case by removing underscores (_ ) and capitalizing each word. The conversion MUST NOT apply to the following abbreviated words: PH, AC, DC and URI. MTCONNECT MUST be converted to MTConnect. See Figure Observations made for DataItem Example for an example.

The name of an Observation type reported in the MTConnectStreams Response Documentresponse document published by an MTConnect Agent in response to a current request or a sample request. is extended when the DataItem::representation is used to further describe that DataItem in the MTConnectDevices Response Documentresponse document published by an MTConnect Agent in response to a probe request.. See Representations for more details.

Properties

Name	Type	Int	Dep	Multiplicity	Description
compositionId	ID	1.4		0..1	identifier of the Composition entity defined in the MTConnectDevices Response Documentresponse document published by an MTConnect Agent in response to a probe request. associated with the data reported for the Observation.
dataItemId	ID	1.0		1	unique identifier of the DataItem associated with this Observation. Observation::dataItemId MUST match the associated DataItem::id defined in the MTConnectDevices Response Documentresponse document published by an MTConnect Agent in response to a probe request..
name	string	1.0		0..1	name of the DataItem associated with this Observation. Observation::name MUST match the associated DataItem::name defined in the MTConnectDevices Response Documentresponse document published by an MTConnect Agent in response to a probe request..
sequence	integer	1.0		1	number representing the sequential position of an occurrence of an observationobserved value of a property at a point in time. in the data buffer of an agentsoftware that collects data published from one or more piece(s) of equipment, organizes that data in a structured manner, and responds to requests for data from client software systems by providing a structured response in the form of a response document that is constructed using the semantic data model of a Standard. . Observation::sequence MUST have a value represented as an unsigned 64-bit value from 1 to \(2^{64}-1\).
subType	DataItemSubTypeEnum	1.2		0..1	subtype of the DataItem associated with this Observation. Observation::subType MUST match the associated DataItem::subType defined in the MTConnectDevices Response Documentresponse document published by an MTConnect Agent in response to a probe request..
timestamp	datetime	1.0		1	most accurate time available to a piece of equipment that represents the point in time that the data reported was measured.
type	DataItemTypeEnum	1.0		1	type of the DataItem associated with this Observation. Observation::type MUST match the associated DataItem::type defined in the MTConnectDevices Response Documentresponse document published by an MTConnect Agent in response to a probe request..
units	UnitEnum	1.0		0..1	units of the DataItem associated with this Observation. Observation::units MUST match the associated DataItem::units defined in the MTConnectDevices Response Documentresponse document published by an MTConnect Agent in response to a probe request..
isUnavailable	boolean (Default: true)	1.0		1	when true, Observation::result is indeterminate. Note 1 to entry: In XML, when isUnavailable is true, the XML CDATA of the Observation MUST be UNAVAILABLE. ```xml <Execution dataItemId=”…” …>UNAVAILABLE</Execution> > Note 2 to entry: In *JSON*, when `isUnavailable` is `true`, the *JSON* `value` of the `Observation` **MUST** be `UNAVAILABLE`. ```json "Execution" : [ { "dataItemId": "..." ..., "value": "UNAVAILABLE" } ]
result	string	1.0		0..1	observationobserved value of a property at a point in time. of the Observation entity. The default value type for Observation::result is string. Note 1 to entry: in XML the Observation::result is the CDATA of the Observation elementconstituent part or a basic unit of identifiable and definable data.. <Execution dataItemId="..." ...>READY</Execution> Note 2 to entry: in JSON the Observation::result is the member value of the Observation object. "Execution" : [ { "dataItemId": "..." ..., "value": "READY" } ]

Relations

Name	Type	Int	Dep	Multiplicity	Description
isObservationOf	Component	1.0		0..*
isObservationOf	Agent	1.0		0..*
isObservationOf	DataItem	1.0		0..*

Subclasses

Name	Int	Dep
Condition	1.1
Event	1.0
Sample	1.0