Rising edge

True for one instant when the input becomes true.

  • Boolean
  • Modelica Standard Library
  • 2 ports
BlockRising edgeKindedgeLibraryLogic

Description

Detects rising edges: the output is true only at the event instant when the input changes from false to true, and false at all other times.

Example

Latch, timer, and sampler Start and stop buttons set and reset a flip-flop, which times the run, gates a signal, and samples the start time.

EnableStartStopEnabled startStart edgeStop edgeRunningRun timeSine 1 Hz0Gated sineClockStart time
In Gradara, select a Rising edge block and press F1, then choose Open example. It opens as a new model in My models, ready to run.

Also in this example:ConstantSine waveClockANDSwitch (logic)RS flip-flopTimerBoolean constantBoolean stepTriggered sampler

Ports

Inputs 1

  • uBoolean

    Boolean input.

Outputs 1

  • yBoolean

    True at the instant u rises, otherwise false.

Equations

Modelica
y = u ∧ ¬u⁻
u⁻ is the value just before the current event; u⁻ = false at t = 0.

Implementation

Modelica Standard Library 4.1.0Modelica.Blocks.Logical.Edge
MSL documentation

Assumptions and limitations

  • The true pulse has zero duration, so it may not be visible in plotted results.
  • Because u⁻ starts false, an input that is true at t = 0 gives y = true at t = 0.

Tips

  • Use it to trigger discrete actions such as Triggered sampler or the S input of RS flip-flop.

See also

Select a block in Gradara and press F1 to open its page offline.