Devices and Components

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MTConnect organizes information and data from a data source (typically a machine) into an information model that defines the relationship between each piece of data and the source of that data. This information model allows an application to interpret the data received from a data source and correlate that data to its original definition, value, and context.

The basic MTConnect information model contains three primary containers: Devices, Device, and Components. These containers are the building blocks used to organize information about a piece of equipment. They also define how the various parts of a piece of equipment relate to each other.

Example Container Structure

The first, or highest, level container in the MTConnect data structure is the Devices container. The Devices container is comprised of one or more Device XML Element(s). The Devices container provides a mechanism for grouping data from multiple Device elements that are providing their data through a common MTConnect Agent. Devices has no attributes and is only used to group data from Device elements together.

The next level container is Device. A Device typically represents a single piece of equipment or a machine. However, it can also represent any logical grouping of components that operate together to perform a function. Every Device in MTConnect® MUST have an Availability data item. Availability represents the device’s ability to provide information about itself. The Device container is compromised of one or more Components XML Elements.

The third container in the MTConnect Data Structure is the Components container(s). Components provides a mechanism for grouping sub-elements of a Device into logical groups that are associated with each other. Components has no attributes and is only used to group Component elements together. The Components container is compromised of one or more Component XML Elements.

Devices

A Device is a XML Element that holds all the Components associated with a piece of equipment. This can be a logical grouping of Component XML Elements that perform a particular function. The Device MUST have an Availability data item that indicates if this device is available to provide information.

In the MTConnect® schema, a Device is actually a unique type of ''Component. A Device supports all of the functions and capabilities defined for a Component. However, it MUST be uniquely identified throughout the MTConnect® Standard and schema as a Device to clearly define the difference between a logical collection of components that function together as a Device and the identification of each Component that forms the structure within a Device.

Device Schema Diagram

Note: Some components may not be integral to a parent device or another component. These components may function independently or produce data that is not relevant to a parent device. An example would be a temperature sensor installed in a plant to monitor the ambient air temperature. In this case, the Component MAY be modeled in the MTConnect schema as a Device. When modeled as a Device, the component MUST provide all of the data and capabilities defined for a Device. It is also possible for these components to be defined as a Component of a parent device and simultaneously as an independent Device; communicating data associated with the parent Device incorporated into that device’s data stream and independently communicating additional data in a separate data stream using its own uuid.

Device Attributes:

Attribute Description Occurrence
iso841Class DEPRECATED in Release 1.1.0 -
uuid A unique identifier that will only refer to this Device. For example, this may be the manufacturer’s code and the serial number. The uuid should be alphanumeric and not exceeding 255 characters. An NMTOKEN XML type. 0..1*
name The name of the Device. This name should be unique within the machine to allow for easier data integration. An NMTOKEN XML type. 1
nativeName The name the device manufacturer assigned to this Device. If the native name is not provided, it MUST be the name. 0..1
id The unique identifier for this Device in the document. An id MUST be unique across all the id attributes in the document. An XML ID-type. 1
sampleRate DEPRECATED IN REL. 1.2 (REPLACED BY sampleInterval) -
sampleInterval The interval in milliseconds between the completion of the reading of one sample of data from a device until the beginning of the next sampling of that data. This is the number of milliseconds between data captures. If the sample interval is smaller than one millisecond, the number can be represented as a floating point number. For example, an interval of 100 microseconds would be 0.1. 0..1**

Notes:

*The uuid MUST be provided for the Device. It is optional for all other Component types.
**The sampleInterval is used to aid an application in interpolating values. This is the desired sample interval and may vary depending on the capabilities of the device.

Device Elements:

Element Description Occurrence
Description An XML element that can contain any descriptive content. This can contain configuration information and manufacturer specific details. 0..1
Configuration An XML element that can contain descriptive content defining the configuration information for a Device. 0..1
Components A container for lower level Component XML Elements associated with this Device. 0..INF*
DataItems The data items (defined below) provided by this Device. The data items define the measured values to be reported by this Device. 0..INF*

Note:

*At least one of Components or DataItems MUST be provided.

Components

A Component XML Element defines physical or logical sub-element of a device. Component is an abstract type and will never appear in the MTConnect XML document. Component elements are represented as XML Element sub-types such as Axes, Controller, Door, etc.

Component elements contain information and data defining the element’s operational state, the environment in which it is functioning, and its health or status. This information and the measured values associated with a component are defined as DataItems. For more information on data items click here.

Component can be further sub-divided into smaller Components XML Elements to provide additional detail on the structure and configuration of a Component. These sub-elements have all the characteristics and capabilities of the parent component.

Component/Sub-component Diagram

While these sub-elements are by definition Components, they SHALL be called subcomponents within the MTConnect Standard to provide clarity on the relationship between the parent component and its associated sub-elements (subcomponents). Additionally, subcomponents may be further subdivided into additional Components, as required, to provide a complete description of a device and its measured values (DataItems). Components and related subcomponents are represented in the XML schema as follows:

	<Devices>
		<Device>
			 <Components>
				 <Axes(Component Type Subcomponent)>
					 <Components>
					  	<Linear (Component Type Subcomponent) >
							 < Components>
							   <Etc.  >
Component Schema

Every component has the following composition:

Attribute Description Occurrence
uuid A unique identifier that will only refer to this Component. For example, this can be the manufacturer’s code and the serial number. The uuid should be alphanumeric and not exceeding 255 characters. An NMTOKEN XML type. 0..1*
name The name of the Component. This name should be unique within the machine to allow for easier data integration. An NMTOKEN XML type. 1
nativeName The name the device manufacturer assigned to the Component. If the native name is not provided it MUST be the name. 0..1
id The unique identifier for this Component in the document. An id MUST be unique across all the id attributes in the document. An XML ID-type. 1
sampleRate DEPRECATED IN REL. 1.2 (REPLACED BY sampleInterval) -
sampleInterval The interval in milliseconds between the completion of the reading of one sample of data from a component until the beginning of the next sampling of that data. This is the number of milliseconds between data captures. If the sample interval is smaller than one millisecond, the number can be represented as a floating point number. For example, an interval of 100 microseconds would be 0.1. 0..1**

Notes:

*The uuid MUST be provided for the Device. It is optional for all other Component types.
**The sampleInterval is used to aid the application in interpolating values. This is the desired sample Interval and may vary depending on the capabilities of the component.

Component Elements:

Element Description Occurrence
Description An element that can contain any descriptive content. This can contain information about the Component and manufacturer specific details. 0..1
Components A container for lower level Component XML Elements associated with this Component. 0..INF*
Configuration An element that can contain descriptive content defining the configuration information for a Component. 0..1
DataItems The data items this component provides. The data items define the measured values to be reported by this Component. 0..INF*

Note:

*At least one of Components or DataItems MUST be provided.

The CDATA of Description is any additional descriptive information the implementer chooses to include regarding the Component. An example of a Description is as follows:

 <Description manufacturer="Example Co" serialNumber="A124FFF"
   station="2"> Example Co Simulated Vertical 3 Axis Machining center.
 </Description>

The information can be provided for any component. For example, an electrical power sensor can be defined as follows:

<Description manufacturer="Example Co" 
   serialNumber="EXCO-TT-099PP-XXXX"> Advanced Pulse watt-hour transducer 
   with pulse output
</Description>