Hit Scheduler

Schedule major time step for variable-step solver

• Library:

• Simulink / Messages & Events

• 

Description

Use the Hit Scheduler block to schedule major time steps for a variable-step solver during simulation. With the Hit Scheduler block, you can implement dynamic solver hit event scheduling based on the behavior of your model during simulation.

To schedule a major time step, you provide the block two inputs:

• En — The enable input controls when the block schedules a time step. The block schedules a time step when the input is logical true.

• Δt — The time interval input specifies when the scheduled time step occurs. The Hit Scheduler block calculates the time hit to schedule, in seconds, as the sum of the current simulation time and the time interval input.

When the simulation reaches the scheduled time hit, the simulation takes a major time step and the block output updates. You can configure the block to produce either a signal output or a function-call output using the Output type parameter.

You can use the Hit Scheduler block to schedule multiple future time steps. The block stores the future time steps in a queue you can configure using the Initial buffer size and Use fixed buffer size parameters.

Ports

Input

En — Enable signal for scheduling time step

scalar

When the enable input value is logical true, the block schedules a simulation time step.

Data Types: Boolean

Δt — Interval between current simulation time and time step to schedule

scalar

The block calculates the time step to schedule, in seconds, as the sum of the current simulation time and the current value of the time interval input.

Data Types: double

Output

Port_1 — Indication of scheduled time step

scalar

The block output updates when the simulation takes a time step the block scheduled. You can configure the block output as a signal or a function-call using the Output type parameter.

• When you set Output type to Signal, the block output becomes logical true when the simulation takes a scheduled time step.

• When you set Output type to Function-Call, the block generates a function-call event when the simulation takes a scheduled time step.

Because the Hit Scheduler block explicitly schedules solver time hits that affect when the block executes, the output has variable sample time for both output types. For more information about variable sample time, see Types of Sample Time.

Data Types: Boolean

Parameters

Output type — Type of block output

Signal (default) | Function Call

When the simulation takes a time step that the block scheduled, the block output updates.

• Signal — Block output becomes logical true when the simulation takes a scheduled time step.

• Function Call — Block generates a function-call event when the simulation takes a scheduled time step.

Programmatic Use

Block Parameter: HitSchedulerOutputType

Type: string | character vector

Values: 'Signal' | 'Function-Call'

Default: 'Signal'

Initial buffer size — Initial size of buffer for scheduled time steps

256 (default) | integer

Specify the size of the buffer that stores scheduled time steps as a positive, scalar integer value.

By default, the buffer size is dynamic so that the software can increase the size if the buffer fills during simulation. When you select Use fixed buffer size, the Initial buffer size parameter value specifies the fixed size for the buffer. If the buffer overflows during simulation, the Hit Scheduler block overwrites scheduled time hits on a first-in, first-out basis.

Programmatic Use

Block Parameter: InitialBufferSize

Type: string | character vector

Values: positive, whole, numeric scalar

Default: '256'

Use fixed buffer size — Option to use fixed-size buffer

off (default) | on

When you select this option, the block uses a fixed buffer size, and the Initial buffer size parameter specifies the size of the buffer. If the buffer overflows during simulation, the Hit Scheduler block overwrites scheduled time hits on a first-in, first-out basis. By default, the buffer size is dynamic so that the software can adjust the size during simulation as needed.

Programmatic Use

Block Parameter: FixedBuffer

Type: string | character vector

Values: 'on' | 'off'

Default: 'off'

Model Examples

Schedule When Traffic Camera Takes Snapshot

Use the Hit Scheduler block to schedule when a traffic camera captures an image of a speeding car.

Open Live Script

Model Effect of Temperature and Jitter on Crystal Oscillation Frequency

Use the Hit Scheduler block to model temperature drift and jitter in crystal oscillator frequency.

Open Live Script

Block Characteristics

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

Version History

Introduced in R2022b