Unit Delay With Preview Resettable (Obsolete)
Output signal and signal delayed by one sample period, with external reset
The Unit Delay With Preview Resettable block is not recommended. This block was removed from the Discrete library in R2016b. In new models, use the Delay block (with parameters set appropriately). Existing models that contain the Unit Delay With Preview Resettable block continue to work for backward compatibility.
Additional Math & Discrete / Additional Discrete (until R2016b)
The Unit Delay With Preview Resettable block supports calculations that have feedback
and depend on the current input. The block can reset its state based on a reset signal
The block has two input ports: one for the input signal
u and one
for the external reset signal
When 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 reset signal
R is true, the block resets the current state
to the initial condition given by the Initial condition parameter.
The first output signal is forced to equal the initial condition. The second output
signal is not affected until one time step later.
This reset action is vectorized and supports 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
Data Type Support
The Unit Delay With Preview Resettable block accepts signals of the following data types:
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
For more information, see Data Types Supported by Simulink in the Simulink® documentation.
- Initial condition
Specify the initial output of the simulation.
- Sample time
Specify the time interval between samples. To inherit the sample time, set this parameter to
-1. See Specify Sample Time in the online documentation for more information.
Double | Single | Boolean | Base Integer | Fixed-Point | Enumerated
Specified in the Sample time parameter
Yes, to first output port
No, to second output port
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