DSP Blockset

Triggered Signal From Workspace

Import signal samples from the MATLAB workspace when triggered

Library

Signal Operations

Description

The Triggered Signal From Workspace block imports signal samples from the MATLAB workspace into the Simulink model when triggered by the control signal at the input port (). The Signal parameter specifies the name of a MATLAB workspace variable containing the signal to import, or any valid MATLAB expression defining a matrix or 3-D array.

When the Signal parameter specifies an M-by-N matrix (M1), each of the N columns is treated as a distinct channel. The frame size is specified by the Samples per frame parameter, M_o, and the output when triggered is an M_o-by-N matrix containing M_o consecutive samples from each signal channel. For M_o=1, the output is sample based; otherwise the output is frame based. For convenience, an imported row vector (M=1) is treated as a single channel, so the output dimension is M_o-by-1.

When the Signal parameter specifies an M-by-N-by-P array, the block generates a single page of the array (an M-by-N matrix) at each trigger time. The Samples per frame parameter must be set to 1, and the output is always sample based.

Trigger Event

The triggering event at the input port is specified by the Trigger type pop-up menu, and can be one of the following:

• Rising edge triggers execution of the block when the trigger input rises from a negative value to zero or a positive value, or from zero to a positive value.
• Falling edge triggers execution of the block when the trigger input falls from a positive value to zero or a negative value, or from zero to a negative value.
• Either edge triggers execution of the block when either a rising or falling edge (as described above) occurs.

Initial and Final Conditions

The Initial output parameter specifies the output of the block from the start of the simulation until the first trigger event arrives. Between trigger events, the block holds the output value constant at its most recent value (that is, no linear interpolation takes place). For single-channel signals, the Initial output parameter value can be a vector of length M_o or a scalar to repeat across the M_o elements of the initial output frames. For matrix outputs (M_o-by-N or M-by-N), the Initial output parameter value can be a vector of length N to repeat across all rows of the initial outputs, or a scalar to repeat across all elements of the initial matrix outputs.

When the block has output all of the available signal samples, it can start again at the beginning of the signal, or simply repeat the final value or generate zeros until the end of the simulation. (The block does not extrapolate the imported signal beyond the last sample.) The Form output after final data value by parameter controls this behavior:

• If Setting To Zero is specified, the block generates zero-valued outputs for the duration of the simulation after generating the last frame of the signal.
• If Holding Final Value is specified, the block repeats the final sample for the duration of the simulation after generating the last frame of the signal.
• If Cyclic Repetition is specified, the block repeats the signal from the beginning after generating the last frame. If there are not enough samples at the end of the signal to fill the final frame, the block zero-pads the final frame as necessary to ensure that the output for each cycle is identical (for example, the ith frame of one cycle contains the same samples as the ith frame of any other cycle).

Dialog Box

Signal

The name of the MATLAB workspace variable from which to import the signal, or a valid MATLAB expression specifying the signal.

Trigger type

The type of event that triggers the block's execution.

Initial output

The value to output until the first trigger event is received.

Samples per frame

The number of samples, M_o, to buffer into each output frame. This value must be 1 if a 3-D array is specified in the Signal parameter.

Form output after final data value by

Specifies the output after all of the specified signal samples have been generated. The block can output zeros for the duration of the simulation (Setting to zero), repeat the final data sample (Holding Final Value) or repeat the entire signal from the beginning (Cyclic Repetition).

Supported Data Types

• Double-precision floating point
• Single-precision floating point

To learn how to convert your data types to the above data types in MATLAB and Simulink, see Supported Data Types and How to Convert to Them.

See Also

From Wave Device	DSP Blockset
From Wave File	DSP Blockset
Signal To Workspace	DSP Blockset
Signal From Workspace	DSP Blockset
Triggered To Workspace	DSP Blockset

See the sections below for related information:

• Discrete-Time Signals
• "Multichannel Signals
• Benefits of Frame-Based Processing
• Creating Signals Using the Signal From Workspace Block
• "Importing Signals

Triggered Delay Line

Triggered To Workspace