WOLFRAM SYSTEM MODELER
FallbackDemonstrates how to switch to a fallback value after a period of Uncertain or Bad status severity |
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Diagram
Wolfram Language
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SystemModel["OPCUA.Examples.Fallback"]
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Information
This example demonstrates how to switch to a fallback value after a period of Uncertain or Bad status severity.
This example requires an OPC UA example server running on localhost.
Read about how to start the example server here.
For all types that can be read by the library, there is a corresponding SetIfGood component (see, for example, the one for a scalar Real) that can be used to propagate the value and its corresponding timestamp, only in the case when severity is UAStatusSeverity.Good.
In this example, that is used in combination with a ElapsedTimeSince to measure the age of the last known value with status severity UAStatusSeverity.Good.
When that age exceeds the specified threshold of 2 s, the model switches to a fallback value.
The purpose of the startStatusSimulation is to start a simulation on the example server that changes the status and value of certain nodes.
Components (10)
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startStatusSimulation |
Type: StartStatusSimulation Description: Block that starts a status simulation on the ExampleServer |
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client |
Type: Client Description: Client for connecting to an OPC UA server |
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readClock |
Type: PeriodicExactClock Description: Generate a periodic clock signal with a period defined by an Integer number with resolution |
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readReal |
Type: Read Description: Adds reading of a Real scalar node to a ReadNodeList |
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setIfGood |
Type: SetIfGood Description: Set the output to the input if severity == Good |
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elapsedTimeSince |
Type: ElapsedTimeSince Description: Output y is the elapsed time in seconds since the input timestamp u |
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fallbackValue |
Type: Constant Description: Generate constant signal of type Real |
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greaterThreshold |
Type: GreaterThreshold Description: Output y is true, if input u is greater than threshold |
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switch |
Type: Switch Description: Switch between two Real signals |
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severityEquals |
Type: SeverityEquals Description: Output y is true if input u is equal to severity |