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Additional Math & Discrete / Additional Discrete
The Unit Delay With Preview Enabled Resettable External RV block supports calculations that have feedback and depend on the current input. The block can reset its state based on a reset signal R.
The block has four input ports: one for the input signal u, one for the external enable signal E, one for the external reset signal R, and one for the external reset value RV.
When the enable signal E is on and the reset signal R is false, the first port outputs the signal and the second port outputs the signal delayed by one sample period.
When the enable signal E is on and the reset signal R is true, the first output signal is forced to equal the reset value RV. The second output signal is not affected until one time step later, at which time it is equal to the reset value RV at the previous time step. The internal Initial condition has a direct effect on the second output only when the model starts or when a parent enabled subsystem is reset.
When the enable signal is off, the block is disabled, and the state and output values do not change, except during resets.
The enable signal is on when E is not 0, and off when E is 0. The enable and reset actions are vectorized and support scalar expansion.
Having two outputs is useful for implementing recursive calculations where the result includes the most recent inputs. The second output can feed back into calculations of the block's inputs without causing an algebraic loop. Meanwhile, the first output shows the most up-to-date calculations.
You specify the time between samples with the Sample time parameter. A setting of -1 means that the block inherits the Sample time.
The Unit Delay With Preview Enabled Resettable External RV block accepts signals of the following data types:
Floating point
Built-in integer
Fixed point
Boolean
Enumerated
The outputs have the same data type as the input u. For enumerated signals, the Initial condition must be of the same enumerated type as the input u.
For more information, see Data Types Supported by Simulink in the Simulink documentation.
Specify the initial output of the simulation.
Specify the time interval between samples. To inherit the sample time, set this parameter to -1. See How to Specify the Sample Time in the online documentation for more information.
Direct Feedthrough | Yes, to first output port No, to second output port |
Sample Time | Specified in the Sample time parameter |
Scalar Expansion | Yes |
Zero-Crossing Detection | No |
Unit Delay, Unit Delay Enabled, Unit Delay Enabled External IC, Unit Delay Enabled Resettable, Unit Delay Enabled Resettable External IC, Unit Delay External IC, Unit Delay Resettable, Unit Delay Resettable External IC, Unit Delay With Preview Enabled, Unit Delay With Preview Enabled Resettable, Unit Delay With Preview Resettable, Unit Delay With Preview Resettable External RV
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