I would use a Triggered Subsystem to do this. The subsystem would be driven by a rising edge in the comparison y=k, so that when this becomes true, the subsystem executes.
Inside the Subsystem, you could put in a "Clock" block so when the subsystem executes, the time is output.
One other note, you may want to do the comparison either with some tolerance or as a "greater than or equal", so you don't miss the event.
- Sebastian
