I needed to trigger a square wave pulse using a signal within my Simulink model (in my case it was a position vector). All I could find within the Sim Library was pulses set to activate at a certain time (by using a delay or building a signal from scratch). So I baked one myself.
The biggest problem was the inability to "reset" the clock (I wanted to use it as a timer to set the width of my pulse). As a substitution for the clock timer, I compare the output of pulse_amplitude => integrator block with the value = pulse_amplitude*pulse_width.