Information

This example demonstrates how to achieve irregular sampling from an OPC UA server using a triggered sampling block.

This example requiers an OPC UA example server running on localhost. Read about how to start the example server here.

A triggered sampling block for reading data of type Real is used to sample data from a table at irregular time intervals. Each time the output from booleanTable is true, data is read from opcServer. The sampled signal is then passed through a lowpass Butterworth filter and used as a reference signal to control the height of the liquid in tank.

Plots of the sampled signal read from node 51031 on opcServer, the written values from the table, and the output from booleanTable. Note how data has been sampled each time the Boolean output trigger is true.

Plot of the reference signal and the height of the liquid in tank.

Components (10)

	opcServer	Type: OPCUAServer Description: A model used for setting up server parameters
	triggeredReadReal	Type: TriggeredRead Description: A block for reading data from items on an OPC server at intervals determined by an external Boolean signal (trigger)
	tank	Type: ControlledTank Description: Model of a simple tank with actuator input
	PI	Type: LimPID Description: P, PI, PD, and PID controller with limited output, anti-windup compensation, setpoint weighting and optional feed-forward
	booleanTable	Type: BooleanTable Description: Generate a Boolean output signal based on a vector of time instants
	const	Type: Constant Description: Generate constant signal of type Real
	gain	Type: Gain Description: Output the product of a gain value with the input signal
	filter	Type: Filter Description: Continuous low pass, high pass, band pass or band stop IIR-filter of type CriticalDamping, Bessel, Butterworth or ChebyshevI
	writeReal	Type: Write Description: A block for writing data to an item on an OPC server at intervals determined by parameter samplePeriod
	combiTimeTable	Type: CombiTimeTable Description: Table look-up with respect to time and linear/periodic extrapolation methods (data from matrix/file)

TriggeredSampling

Diagram

Wolfram Language

Information

Components (10)