Clock

R2026b

Display and provide simulation time

• 

Clock block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Simulink / Sources

Description

The Clock block outputs the current simulation time at each simulation step. This block is useful for other blocks that need the simulation time.

When you need the current time within a discrete system, use the Digital Clock block.

Examples

Calculate and Display Simulation Step Size using Memory and Clock Blocks

This example shows how to use the Memory and Clock blocks to calculate and display the step size in a simulation. The Sum block subtracts the time at the previous time step, which the Memory block generates, from the current time, which the Clock block generates.

Because Inherit sample time is not selected for the Memory block, the block sample time depends on the type of solver for simulating the model. In this case, the model uses a fixed-step solver. Therefore, the sample time of the Memory block is the solver step size, or 1.

If you replace the Memory block with a Unit Delay block, you get the same results. The Unit Delay block inherits a discrete sample time of 1.

Extended Examples

Inverted Pendulum with Animation

Use Simulink® to model and animate an inverted pendulum system. An inverted pendulum has its center of mass above its pivot point. To stably maintain this position, the system implements control logic to move the pivot point below the center-of mass as the pendulum starts to fall. The inverted pendulum is a classic dynamics problem used to test control strategies.

• Open Model

Accurate Zero-Crossing Detection

How zero-crossing detection works in Simulink®. Simulink uses zero-crossing detection to accurately simulate an abrupt model change or discontinuity without decreasing the solver time steps. For more information, see Zero-Crossing Detection.

• Open Model

Ports

Output

Port_1 — Sample time

scalar

Sample time, specified as the current simulation time at each simulation time step.

Data Types: double

Parameters

Display time — Display simulation time on block icon

off (default) | on

Select this check box to display the simulation time as part of the Clock block icon. When you clear this check box, the simulation time does not appear on the block icon.

Programmatic Use

Block Parameter: DisplayTime

Type: character vector

Values: 'off' | 'on'

Default: 'off'

Decimation — Interval at which to update block icon

10 (default) | positive integer

Specify the interval at which Simulink^® updates the Clock icon as a positive integer.

Suppose that the decimation is 1000. For a fixed integration step of 1 millisecond, the Clock icon updates at 1 second, 2 seconds, and so on.

Dependencies

To display the simulation time on the block icon, you must select the Display time check box.

Programmatic Use

Block Parameter: Decimation

Type: character vector

Value: scalar

Default: '10'

Block Characteristics

Data Types	double
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"simulink/Sources/Clock"

Example: add_block("simulink/Sources/Clock","myModel/myBlock",MakeNameUnique="on")

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

Not recommended for production code. Relates to resource limits and restrictions on speed and memory often found in embedded systems. Generated code can contain dynamic allocation and freeing of memory, recursion, additional memory overhead, and widely-varying execution times. While the code is functionally valid and generally acceptable in resource-rich environments, smaller embedded targets often cannot support such code. Usually, blocks evolve toward being suitable for production code. Thus, blocks suitable for production code remain suitable.

Version History

Introduced before R2006a