Unit Delay Enabled Resettable (Obsolete)

Delay signal one sample period, if external enable signal is on, with external Boolean reset


The Unit Delay Enabled 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 Enabled Resettable block continue to work for backward compatibility.


Additional Math & Discrete / Additional Discrete (until R2016b)


The Unit Delay Enabled Resettable block combines the features of the Unit Delay Enabled (Obsolete) and Unit Delay Resettable (Obsolete) blocks.

The block can reset its state based on an external reset signal R. When the enable signal E is on and the reset signal R is false, the block outputs the input signal delayed by one sample period.

When the enable signal E is on and the reset signal R is true, the block resets the current state and its output to the Initial condition.

When the enable signal is off, the block is disabled, and the state and output do not change except for resets. The enable signal is on when E is not 0, and off when E is 0.

You specify the time between samples with the Sample time parameter. A setting of -1 means that the block inherits the Sample time.

Data Type Support

The Unit Delay Enabled Resettable block accepts signals of the following data types:

  • Floating point

  • Built-in integer

  • Fixed point

  • Boolean

  • Enumerated

The output has 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.


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.


Data Types

Double | Single | Boolean | Base Integer | Fixed-Point | Enumerated

Sample Time

Specified in the Sample time parameter

Direct Feedthrough

No, of the input port

No, of the enable port

Yes, of the reset port

Multidimensional Signals


Variable-Size Signals


Zero-Crossing Detection


Code Generation


Introduced before R2006a