FB_SquareWave (Function Block)

Generates a square wave signal.

The raw wave alternates between +1 and -1 over one period. Amplitude scales the wave and Bias shifts it vertically, giving an output that swings between Bias + Amplitude and Bias - Amplitude.

Phase shifts the wave horizontally in radians. A phase of π starts the wave in its low half-cycle, a phase of -π has the same effect.

Note

The block is FINAL and must be instantiated, not extended. Use FB_init to set tPeriod, fAmplitude, fBias, and fPhase at declaration time.

Extends: FB_PeriodicSignal

Methods

FB_init

Inputs

Name	Type	Description
`bInitRetains`	`BOOL`	if TRUE, the retain variables are initialized (warm start / cold start)
`bInCopyCode`	`BOOL`	if TRUE, the instance afterwards gets moved into the copy code (online change)
`tPeriod`	`LTIME`	Duration of one full cycle.
`fAmplitude`	`LREAL`	Scales the ±1 wave. Output swings between Bias ± Amplitude.
`fBias`	`LREAL`	Shifts the output up or down by a fixed value.
`fPhase`	`LREAL`	Phase offset in radians. Shifts the wave horizontally. Negative values shift in the opposite direction.

Reset

Restarts the wave from the beginning by resetting the accumulated time to zero. The phase, amplitude, and bias are unaffected.

Run

Advances the square wave by one time step.

Note

Must be called once per cycle on a single PLC task. If the measured cycle time is zero or Period is zero, the method returns early without updating the output.