Component Types and Subcomponents
Component is an abstract type that allows for extensibility. As the specification progresses, more component types will be added to support new devices and parts of new devices. Some examples of component types are Axes, Controller, and Systems. Any of these component types can have data items and subcomponents. Appendix B contains reference models for common equipment to guide developers in implementing MTConnect on their devices.
Axes is the root of all device components that have linear or rotational motion. Currently there are only Linear and Rotary axes supported and when axes are defined the Axes component MUST contain at least one Linear or Rotary axis. The Linear axes MUST be named X, Y, Z with numbers appended for additional axes in the same plane, for example X2, Y2, and Z2 are the secondary axes to X, Y, and Z. Rotary axes MUST be named A, B, and C and rotate around the X, Y, and Z axes respectively. As with the Linear axes, a number MUST be appended for additional axes in the same plane.
The Axes represent the physical data for the axis components. When data is defined specifically for the physical axes, positions MUST be given in MACHINE coordinates. The WORK coordinates are represented in the Path component of the Controller.
DEPRECATION WARNING: In Version 1.1 of the MTConnect® standard, the Spindle component was no longer supported. The Spindle will now be represented by a rotary axis that has a RotaryMode of SPINDLE. The S(n) axis nomenclature SHOULD be removed and replaced with A, B, or C to clearly identify which primary plane the rotary axis is rotating around. All associated DataItems SHOULD now be named accordingly.
Note: The convention for multiple linear and rotary axes having the same designation is to index the axes letter with a number. For this standard, the secondary axis number starts at 2 (i.e. X, X2, X3, … or C, C2, C3, C4, …). This is in compliance with the ISO-841-2001.
Figure one below shows an axes example with three linear axes and one rotary axis.
- A linear axis represents the movement of a physical device, or a portion of a device, in a straight line. Movement may be in either a positive or negative direction.
- An axis whose function is to provide rotary motion may function as a continuous rotation (i.e. spindle mode), continuous-path contour cutting in a rotary motion (i.e. contouring), or repositioning (i.e. indexing) different faces of the part. As such, a rotary axis MUST operate in one of the three following modes: SPINDLE, INDEX, or CONTOUR.
The Controller component represents an intelligent device. Examples include a CNC (Computer Numerical Control) or PAC (Programmable Automation Control) which may be referred to as a Motion Control or General Purpose Motion Control. The Controller provides information regarding the execution of a control program and the execution state of the device. There are no required subcomponents of the Controller.
Note: MTConnect Version 1.1.0 and later implementations SHOULD use a Path sub-component to represent an individual tool path and execution state (see Path). When the machine is capable of executing more than one simultaneous program, the implementation MUST use the Path component.
For more complex devices and controllers, each path will be represented by a Path subcomponent. A Path represents the motion of a control point as it moves through space as controlled by a set of control instructions (i.e. vector move). The Path will encapsulate the position, feedrate, and rotation of the control point as presented by the controller. The control point is the positioning of a tool at a point in space.
This component represents a door closure that can be opened or closed. It MUST have a DataItem called DoorState to indicate if it is opened, closed or unlatched. A device may contain multiple door components.
An Actuator is a device for moving or controlling a mechanism or system. It takes energy, usually transported by air, electric current, or liquid and converts it into some kind of motion. An Actuator may be a Component of a Device or it may be a subcomponent of a parent Component.
Sensor is an abstract type component that provides measurement data related to a Device or Component. Depending on the type of data provided by the sensor, it may be modeled in the XML schema in different ways. However, it will always be modeled to associate the data contained in Sensor with the Component XML Element to which the data is most closely associated.
A sensor is typically comprised of two major components – the sensing element (provides a signal or measured value) and the sensor interface (signal processing, conversion, and communications). In MTConnect, the sensor interface is modeled as a Component called Sensor. The sensing element or measured value is modeled as a DataItem. Example: A pressure transducer could be modeled as a Sensor (Component) with a name = Pressure Transducer B and its measured value could be modeled as a DataItem of type PRESSURE.
Sensor MUST NOT be modeled in the plural. Sensor will always refer to the sensor interface. Each sensor interface may have multiple sensing elements; each representing the data for a variety of measured values.
The most basic implementation of a sensing element is the providing of a measured value associated with a Component which is the Sensor data. An example would be the measured value of the Temperature of the spindle (Rotary Axis C). This would be represented as a DataItem called Temperature that is associated with the Rotary Axis C as follows:
<Components> <Axes <Components> <Rotary id="c" name="C"> <DataItems> <DataItem type="TEMPERATURE" id="ctemp" category="SAMPLE" name="Stemp" units="DEGREE"/> </DataItems> </Rotary> </Components> </Axes> </Components>
Sensing element(s) are most typically connected to a sensor interface. The sensor interface provides additional information concerning the sensing element(s).
Typical functions of the sensor interface include:
- convert low level signals from the sensing elements into data that can be used by other devices. (Example: Convert a non-linear millivolt signal from a temperature sensor into a scaled temperature value that can be transmitted to another device.)
- process sensing element data into calculated values. (Example: temperature sensor data is converted into calculated values of average temperature, maximum temperature, minimum temperature, etc.)
- provide calibration and configuration information associated with each sensing element.
- monitor the health and integrity of the sensing elements and the sensor interface. (Example: The sensor interface may provide diagnostics on each sensing element (e.g. open wire detection) and itself (e.g. measure internal temperature of the sensor interface).
The sensor interface is modeled in the XML schema as a Component called Sensor. Sensor SHOULD be modeled in the XML schema so that the Sensor is represented as part of the Component to which it is most closely associated.
Example 1: If Sensor provides vibration measurement data for the spindle, it should be modeled as a Sensor for Rotary Axis C.
<Components> <Axes> <Components> <Rotary id="c" name="C"> <Sensor id="spdlm" name="Spindlemonitor"> <DataItems> <DataItem type="DISPLACEMENT" id="cvib" category="SAMPLE" name="Svib" units="MILLIMETER"/> </DataItems> </Sensor> </Rotary> </Components> </Axes> </Components>
Example 2: If Sensor provides measurement data for multiple Components within a Device and is not associated with any particular Component, it MAY be modeled in the XML schema as an independent Component of the Device.
<Device id="d1" uuid="HM1" name="HMC_3Axis"> <Description>3 Axis Mill</Description> <Components> <Sensor id="sensor" name="sensor"/> <DataItems> <DataItem type="TEMPERATURE" id="sentemp" category="SAMPLE" name="Sensortemp" units="DEGREE"/> </DataItems> </Components> </Device>
While Sensor MAY be modeled in different ways in the XML schema, the measured value of the sensing element MUST always be modeled as a DataItem associated with the Component to which the measured value is most closely associated.
The following represents a sensor with two sensing elements, one measures spindle vibration and the other measures the temperature for the X axis. The sensor also has a sensing element measuring the internal temperature of the sensor interface:
<Device id="d1" uuid="HM1" name="HMC_3Axis"> <Description>3 Axis Mill</Description> <Components> <Sensor id="sens1" name="Sensorunit"> <DataItems> <DataItem type="TEMPERATURE" id="sentemp" category="SAMPLE" name="Sensortemp" units="DEGREE"/> </DataItems> </Sensor> <Axes> <Components> <Rotary id="c" name="C"> <DataItems> <DataItem type="DISPLACEMENT" id="cvib" category="SAMPLE" name="Svib" units="MILLIMETER"/> </DataItems> </Rotary> <Linear id="x" name="X"> <DataItems> <DataItem type="TEMPERATURE" id="xt" category="SAMPLE" name="Xtemp" units="DEGREE"/> </DataItems> </Linear> </Components> </Axes> </Components> </Device>
Sensor as a Device
Examples of a sensor functioning as a Device would be a sensor used to monitor the ambient temperature of a building or an air quality monitoring system. Another example would be a vibration monitoring system that is moved from one machine to another. In these cases, the sensor functions as an intelligent device performing a specific function.
<Device id="s1" uuid="HM1" name="AMBIENT_MONITOR"> <Description>Ambient Temperature Monitor</Description> <DataItems> <DataItem type="TEMPERATURE" id="ambtemp" category="SAMPLE" name="Ambienttemp" units="DEGREE"/> </DataItems> </Device>
The Sensor configuration data provides information required for maintenance and support of the sensor.
When Sensor represents the sensor interface for multiple sensing element(s), each sensing element is represented by a Channel. Each Channel represents one sensing element and can have its own attributes and Configuration data.