Industrial Automation - Basics

A stacklight is used to visually or acoustically indicate the state or a specific event of an automation component. It is widely used in various areas of industrial automation. In Figure 1, examples of stacklights are given. They can vary in colours they display or acoustical signals they produce.

Figure 1 Examples of stacklights

This section defines base modelling constructs to represent stacklights in an OPC UA Information Model. It does not define the relations to the triggers of a specific visualization or acoustic signal, like an Alarm or a specific Value of a Variable.

5.2 OPC UA ObjectTypes

5.2.1 BasicStacklightType

Figure 2 BasicStacklightType overview

The BasicStacklightType is the entry point to a stacklight. It contains the elements of the stacklight as well as additional information valid for the whole unit. In Figure 2, a graphical overview is given. It is formally defined in Table 12.

Table 12 – BasicStacklightType Definition

Attribute	Value
BrowseName	BasicStacklightType
IsAbstract	False
Description	Entry point to a stacklight containing elements of the stacklight as well as additional information valid for the whole unit.
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the OrderedListType defined in OPC 10001-13, i.e. inheriting the InstanceDeclarations of that Node.
0:HasProperty	Variable	StacklightMode	StacklightOperationMode	0:PropertyType	M
0:HasComponent	Object	StackLevel		StackLevelType	O
0:HasComponent	Object	StackRunning		StackRunningType	O
0:HasOrderedComponent	Object	0:<OrderedObject>		StackElementType	OP

StacklightMode shows in what way (stack of individual lights, level meter, running light) the stacklight unit is used.

StackLevel is only valid if the stacklight is used in “Levelmeter” StacklightMode. If so, the whole stack is controlled by a single percentual value. In this case, the SignalOn parameter of any <OrderedObject > of StackElementLightType has no meaning.

StackRunning is only valid if the stacklight is used in “Running_Light” StacklightMode.

The ordered component(s) <OrderedObject > represent the stack elements (lamps and acoustic elements) the stacklight is composed of. The HasOrderedComponent Reference shall represent the ordering from the base of the stacklight.

The InstanceDeclarations of the BasicStacklightType have the Attribute values defined in Table 13.

Table 13 – BasicStacklightType Attribute values for child Nodes

Source Path	Value	Description
StacklightMode	-	Shows in what way (stack of individual lights, level meter, running light) the stacklight unit is used.
StackLevel	-	Valid if the stacklight is used in “Levelmeter” StacklightMode. If so, the whole stack is controlled by a single percentual value. In this case, the SignalOn parameter of any stack element of StackElementLightType has no meaning.
StackRunning	-	Valid if the stacklight is used in “Running_Light” StacklightMode.
0:<OrderedObject>	-	Represent the stack elements (lamps and acoustic elements) the stacklight is composed of. The HasOrderedComponent Reference shall represent the ordering from the base of the stacklight.

5.2.2 StacklightType

Figure 3 StacklightType overview

The StacklightType is a subtype of the BasicStacklightType. It adds the possibility to show the stacklight’s health status. In Figure 3, a graphical overview is given. It is formally defined in Table 14.

Table 14 – StacklightType Definition

Attribute	Value
BrowseName	StacklightType
IsAbstract	False
Description	Entry point to a stacklight with the possibility to show the stacklight’s health status.
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the BasicStacklightType defined in 5.2.1, i.e. inheriting the InstanceDeclarations of that Node.
0:HasInterface	ObjectType	2:IDeviceHealthType
Properties of the 2:IDeviceHealthType
0:HasComponent	Variable	2:DeviceHealth	2:DeviceHealthEnumeration	0:BaseDataVariableType	O
0:HasComponent	Object	2:DeviceHealthAlarms		0:FolderType	O

DeviceHealth, defined in IDeviceHealthType, indicates the health status of the stacklight and shall be used as specified in OPC 10000-100.

DeviceHealthAlarms, defined in IDeviceHealthType, can be used to expose alarm instances and shall be used as specified in OPC 10000-100.

The InstanceDeclarations of the StacklightType have the Attribute values defined in Table 15.

Table 15 – StacklightType Attribute values for child Nodes

Source Path	Value	Description
2:DeviceHealth	-	Contains the health status information of the stacklight.
2:DeviceHealthAlarms	-	Contains alarms of the stacklights providing more detailed information on the health of the stacklight.

5.2.3 StackLevelType

Figure 4 StackLevelType overview

The StackLevelType contains the information relevant to a stacklight operating as a level meter. The whole stack is controlled by a percentual value. In Figure 4, a graphical overview is given. It is formally defined in Table 16.

Table 16 – StackLevelType Definition

Attribute	Value
BrowseName	StackLevelType
IsAbstract	False
Description	Contains information relevant to a stacklight operating as a level meter. The whole stack is controlled by a percentual value.
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the BaseObjectType defined in OPC 10000-5 i.e. inheriting the InstanceDeclarations of that Node.
0:HasComponent	Variable	LevelPercent	0:Float	0:AnalogItemType	M
0:HasComponent	Variable	DisplayMode	LevelDisplayMode	0:BaseDataVariableType	M

LevelPercent shows the percentual value the stacklight is representing. The mandatory EURange Property of the Variable indicates the lowest and highest value and thereby allows to calculate the percentage represented by the value. The lowest value is interpreted as 0 percent, the highest is interpreted as 100 percent.

DisplayMode indicates in what way the percentual value is displayed with the stacklight.

The InstanceDeclarations of the StackLevelType have the Attribute values defined in Table 17.

Table 17 – StackLevelType Attribute values for child Nodes

Source Path	Value	Description
LevelPercent	-	Shows the percentual value the stacklight is representing. The mandatory EURange Property of the Variable indicates the lowest and highest value and thereby allows to calculate the percentage represented by the value. The lowest value is interpreted as 0 percent, the highest is interpreted as 100 percent.
DisplayMode	-	Indicates in what way the percentual value is displayed with the stacklight.

5.2.4 StackRunningType

The StackRunningType contains the information relevant to a stacklight operating as a running light. This base type does not define any specific information, but can be extended. This Object is only of relevance when the StacklightMode is in mode “Running_Light”. It is formally defined in Table 18.

Table 18 – StackRunningType Definition

Attribute	Value
BrowseName	StackRunningType
IsAbstract	False
Description	Contains information relevant to a stacklight operating as a running light. This base type does not define any specific information, but can be extended.
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the BaseObjectType defined in OPC 10000-5 i.e. inheriting the InstanceDeclarations of that Node.

5.2.5 StackElementType

Figure 5 StackElementType overview

The StackElementType is the base class for elements in a stacklight. The elements are used in an ordered list. In Figure 5, a graphical overview is given. It is formally defined in Table 19.

Table 19 – StackElementType Definition

Attribute	Value
BrowseName	StackElementType
IsAbstract	True
Description	Base class for elements in a stacklight.
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the BaseObjectType defined in OPC 10000-5 i.e. inheriting the InstanceDeclarations of that Node.
0:HasInterface	ObjectType	0:IOrderedObjectType
0:HasProperty	Variable	SignalOn	0:Boolean	0:PropertyType	O
0:HasProperty	Variable	IsPartOfBase	0:Boolean	0:PropertyType	O
0:HasProperty	Variable	0:NumberInList	0:UInteger	0:PropertyType	M

SignalOn indicates if the signal emitted by the stack element is currently switched on or not.

IsPartOfBase indicates, if the element is contained in the mounting base of the stacklight. All elements contained in the mounting base shall be at the beginning of the list of stack elements.

NumberInList is defined in the IOrderedObjectType and used in conjunction with the HasOrderedComponent Reference of the BasicStacklightType. It shall contain the same ordering information as the Reference and enumerate the stacklight elements counting upwards beginning from the base of the stacklight.

The InstanceDeclarations of the StackElementType have the Attribute values defined in Table 20.

Table 20 – StackElementType Attribute values for child Nodes

Source Path	Value	Description
SignalOn	-	Indicates if the signal emitted by the stack element is currently switched on or not.
IsPartOfBase	-	Indicates, if the element is contained in the mounting base of the stacklight. All elements contained in the mounting base shall be at the beginning of the list of stack elements.
0:NumberInList	-	Enumerate the stacklight elements counting upwards beginning from the base of the stacklight.

5.2.6 StackElementLightType

Figure 6 StackElementLightType overview

The StackElementLightType represents a lamp element in a stacklight. In Figure 6, a graphical overview is given. It is formally defined in Table 21.

Table 21 – StackElementLightType Definition

Attribute	Value
BrowseName	StackElementLightType
IsAbstract	False
Description	Represents a lamp element in a stacklight.
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the StackElementType defined in 5.2.5, i.e. inheriting the InstanceDeclarations of that Node.
0:HasComponent	Variable	SignalColor	SignalColor	0:BaseDataVariableType	O
0:HasComponent	Variable	SignalMode	SignalModeLight	0:BaseDataVariableType	O
0:HasComponent	Variable	Intensity	0:Float	0:AnalogItemType	O
0:HasComponent	Object	<ControlChannel>		ControlChannelType	OP

For the StackElementLightType, either the Variables SignalColor, SignalOn, SignalMode and Intensity shall be used to indicate the respective values for the lamp element or separate ControlChannels per available and individually controllable colour channel shall be used (e.g. in RGB or RGBW lamp elements). The two concepts shall not be used in conjunction in a single StackElementLightType instance.

SignalColor indicates the colour the lamp element has when switched on.

SignalMode shows in what way the lamp is used (continuous light, flashing, blinking) when switched on.

Intensity shows the intensity of the lamp, thus its brightness. The mandatory EURange Property of the Variable indicates the lowest and highest value and thereby allows to calculate the percentage represented by the value. The lowest value is interpreted as 0 percent, the highest is interpreted as 100 percent.

The list of <ControlChannel> instances shows the control information for each independent colour channel of the stacked element.

The InstanceDeclarations of the StackElementLightType have the Attribute values defined in Table 22.

Table 22 – StackElementLightType Attribute values for child Nodes

Source Path	Value	Description
SignalColor	-	Indicates the colour the lamp element has when switched on.
SignalMode	-	Shows in what way the lamp is used (continuous light, flashing, blinking) when switched on.
Intensity	-	Intensity of the lamp, thus its brightness. The mandatory EURange Property of the Variable indicates the lowest and highest value and thereby allows to calculate the percentage represented by the value. The lowest value is interpreted as 0 percent, the highest is interpreted as 100 percent.
<ControlChannel>	-	The list of <ControlChannel> instances shows the control information for each independent colour channel of the stacked element.

5.2.7 StackElementAcousticType

Figure 7 StackElementAcousticType overview

The StackElementAcousticType represents an acoustic element in a stacklight. In Figure 7, a graphical overview is given. It is formally defined in Table 23.

Table 23 – StackElementAcousticType Definition

Attribute	Value
BrowseName	StackElementAcousticType
IsAbstract	False
Description	Represents an acoustic element in a stacklight.
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the StackElementType defined in 5.2.5, i.e. inheriting the InstanceDeclarations of that Node.
0:HasComponent	Variable	OperationMode	0:UInteger	0:BaseDataVariableType	M
0:HasComponent	Variable	Intensity	0:Float	0:AnalogItemType	O
0:HasComponent	Object	AcousticSignals		0:OrderedListType	M

OperationMode indicates what signal of the list of AcousticSignalType nodes is played when the acoustic element is switched on. It shall contain an index matching the NumberInList Property of the respective AcousticSignalType Object of AcousticSignals.

Intensity indicates the sound pressure level of the acoustic signal when switched on. This value shall only have positive values. The mandatory EURange Property of the Variable indicates the lowest and highest value and thereby allows to calculate the percentage represented by the value. The lowest value is interpreted as 0 percent, the highest is interpreted as 100 percent.

AcousticSignals contains a list of audio signals used by this acoustic stacklight element.

The components of the StackElementAcousticType have additional References which are defined in Table 24.

Table 24 – StackElementAcousticType Additional Subcomponents

Source Path	References	NodeClass	BrowseName	DataType	TypeDefinition	Others
AcousticSignals	0:HasOrderedComponent	Object	0:<OrderedObject>		AcousticSignalType	MP

The InstanceDeclarations of the StackElementAcousticType have the Attribute values defined in Table 25.

Table 25 – StackElementAcousticType Attribute values for child Nodes

Source Path

Value

Description

OperationMode

Indicates what signal of the list of AcousticSignalType nodes is played when the acoustic element is switched on. It shall contain an index into the NumberInList of the respective AcousticSignalType Object of AcousticSignals.

Intensity

Indicates the sound pressure level of the acoustic signal when switched on. This value shall only have positive values. The mandatory EURange Property of the Variable indicates the lowest and highest value and thereby allows to calculate the percentage represented by the value. The lowest value is interpreted as 0 percent, the highest is interpreted as 100 percent.

AcousticSignals

Contains a list of audio signals used by this acoustic stacklight element.

AcousticSignals

0:<OrderedObject>

Represents an acoustic signal.

5.2.8 ControlChannelType

Figure 8 ControlChannelType overview

The ControlChannelType is used for control channels of single colour elements within a stack element (e.g. RGB elements would use three ControlChannels, one for each controllable colour). In Figure 8, a graphical overview is given. It is formally defined in Table 26.

Table 26 – ControlChannelType Definition

Attribute	Value
BrowseName	ControlChannelType
IsAbstract	False
Description	Used for control channels of single colour elements within a stack element (e.g. RGB elements would use three ControlChannels, one for each controllable colour).
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the BaseObjectType defined in OPC 10000-5 i.e. inheriting the InstanceDeclarations of that Node.
0:HasProperty	Variable	SignalOn	0:Boolean	0:PropertyType	M
0:HasComponent	Variable	ChannelColor	SignalColor	0:BaseDataVariableType	M
0:HasComponent	Variable	SignalMode	SignalModeLight	0:BaseDataVariableType	M
0:HasComponent	Variable	Intensity	0:Float	0:AnalogItemType	O

SignalOn indicates if the colour is switched on.

ChannelColor shows the channel’s colour.

SignalMode indicates in what mode (continuously on, blinking, flashing) the channel operates when switched on.

Intensity shows the channel’s intensity, thus its brightness. The mandatory EURange Property of the Variable indicates the lowest and highest value and thereby allows to calculate the percentage represented by the value. The lowest value is interpreted as 0 percent, the highest is interpreted as 100 percent.

The InstanceDeclarations of the ControlChannelType have the Attribute values defined in Table 27.

Table 27 – ControlChannelType Attribute values for child Nodes

Source Path	Value	Description
SignalOn	-	Indicates if the colour is switched on.
ChannelColor	-	Indicates in what mode (continuously on, blinking, flashing) the channel operates when switched on.
SignalMode	-	Contains a list of audio signals used by this acoustic stacklight element.
Intensity	-	Shows the channel’s intensity, thus its brightness. The mandatory EURange Property of the Variable indicates the lowest and highest value and thereby allows to calculate the percentage represented by the value. The lowest value is interpreted as 0 percent, the highest is interpreted as 100 percent.

5.2.9 AcousticSignalType

Figure 9 AcousticSignalType overview

The AcousticSignalType represents an acoustic signal. It is used in an ordered list. In Figure 9, a graphical overview is given. It is formally defined in Table 28.

Table 28 – AcousticSignalType Definition

Attribute	Value
BrowseName	AcousticSignalType
IsAbstract	False
Description	Represents an acoustic signal.
References	Node Class	BrowseName	DataType	TypeDefinition	Other
Subtype of the BaseObjectType defined in OPC 10000-5, i.e. inheriting the InstanceDeclarations of that Node.
0:HasInterface	ObjectType	0:IOrderedObjectType
0:HasProperty	Variable	0:NumberInList	0:UInteger	0:PropertyType	M
0:HasComponent	Variable	AudioSample	0:AudioDataType	0:BaseDataVariableType	O

The Description Attribute of each Object of type AcousticSignalType should be used as textual description of the audio signal, e.g. “Buzzer 100Hz”.

NumberInList is defined in IOrderedObjectType and used in conjunction with the HasOrderedComponent Reference of the AcousticSignals Object. Instances of StackElementAcousticType index into this number using the OperationMode Property.

AudioSample contains the audio data, e.g. for devices capable of audio playback.

The InstanceDeclarations of the AcousticSignalType have the Attribute values defined in Table 29.

Table 29 – AcousticSignalType Attribute values for child Nodes

Source Path	Value	Description
0:NumberInList	-	Enumerate the acoustic signals. Instances of StackElementAcousticType index into this number using the OperationMode Property.
AudioSample	-	Contains the audio data, e.g. for devices capable of audio playback.

5.3 OPC UA DataTypes

5.3.1 StacklightOperationMode

The StacklightOperationMode Enumeration DataType contains the values used to indicate how a stacklight (as a whole unit) is used. The contents of its EnumStrings are defined in Table 30.

Table 30 – StacklightOperationMode EnumStrings Fields

Name	Value	Description
Segmented	0	Stacklight is used as stack of individual lights
Levelmeter	1	Stacklight is used as level meter
Running_Light	2	The whole stack acts as a running light
Other	3	Stacklight is used in a way not defined in this version of the specification

Its representation in the AddressSpace is defined in Table 31.

Table 31 – StacklightOperationMode Definition

Attribute		Value
BrowseName		StacklightOperationMode
IsAbstract		False
Description		Contains the values used to indicate how a stacklight (as a whole unit) is used.
References	NodeClass		BrowseName	DataType	TypeDefinition	Other
Subtype of the Enumeration type defined in OPC 10000-3
0:HasProperty	Variable		0:EnumValues	0:EnumValueType[]	0:PropertyType	M

5.3.2 LevelDisplayMode

The LevelDisplayMode Enumeration DataType contains the values used to indicate how a percentual value is displayed if the stacklight unit works in Levelmeter mode. The contents of its EnumStrings are defined in Table 32.

Table 32 – LevelDisplayMode EnumStrings Fields

Name	Value	Description
Dimmed	0	Uses dimming to display fractions.
Blinking	1	Uses blinking to display fractions.
Other	2	Display fractions in a way not defined in this version of the specification.

Its representation in the AddressSpace is defined in Table 33.

Table 33 – LevelDisplayMode Definition

Attribute		Value
BrowseName		LevelDisplayMode
IsAbstract		False
Description		Contains the values used to indicate how a percentual value is displayed if the stacklight unit works in Levelmeter mode.
References	NodeClass		BrowseName	DataType	TypeDefinition	Other
Subtype of the Enumeration type defined in OPC 10000-3
0:HasProperty	Variable		0:EnumValues	0:EnumValueType[]	0:PropertyType	M

5.3.3 SignalColor

The SignalColor Enumeration DataType holds the possible colour values for stacklight lamps. The contents of its EnumStrings are defined in Table 34.

Table 34 – SignalColor EnumStrings Fields

Name	Value	Description
Off	0	Element is disabled.
Red	1	This value indicates a red lamp colour.
Green	2	This value indicates a green lamp colour.
Blue	3	This value indicates a blue lamp colour.
Yellow	4	This value indicates a yellow lamp colour (R+G).
Purple	5	This value indicates a purple lamp colour (R+B).
Cyan	6	This value indicates a cyan lamp colour (G+B).
White	7	This value indicates a white lamp colour (R+G+B).

Note: If you are using the IEC60073 you shall use the colours Red, Green, Blue, Yellow and White.

Its representation in the AddressSpace is defined in Table 35.

Table 35 – SignalColor Definition

Attribute		Value
BrowseName		SignalColor
IsAbstract		False
Description		Holds the possible colour values for stacklight lamps.
References	NodeClass		BrowseName	DataType	TypeDefinition	Other
Subtype of the Enumeration type defined in OPC 10000-3
0:HasProperty	Variable		0:EnumValues	0:EnumValueType[]	0:PropertyType	M

5.3.4 SignalModeLight

SignalModeLight contains the values used to indicate in what way a lamp behaves when switched on. The contents of its EnumStrings are defined in Table 36.

Table 36 – SignalModeLight EnumStrings Fields

Name	Value	Description
Continuous	0	This value indicates a continuous light.
Blinking	1	This value indicates a blinking light (blinking in regular intervals with equally long on and off times).
Flashing	2	This value indicates a flashing light (blinking in intervals with longer off times than on times, per interval multiple on times are possible).
Other	3	The light is handled in a way not defined in this version of the specification.

Its representation in the AddressSpace is defined in Table 37.

Table 37 – SignalModeLight Definition

Attribute		Value
BrowseName		SignalModeLight
IsAbstract		False
Description		Contains the values used to indicate in what way a lamp behaves when switched on.
References	NodeClass		BrowseName	DataType	TypeDefinition	Other
Subtype of the Enumeration type defined in OPC 10000-3
0:HasProperty	Variable		0:EnumValues	0:EnumValueType[]	0:PropertyType	M