IOPLL output clock issue Stratix10

SignalTap uses a clock to capture the data, so it's dependent on that clock rate. For logic, you want it to be the same clock that drives the logic you're tapping, as you need to synchronously tap it. For probing a clock, I'm not sure exactly what you're hoping to see. Normally people have the clock drive a counter and then just sample that with another clock, to calculate X transitions happened in Y time.

Regards,

Richard Tan