How to program ...

I'm only experienced in using siemens step7 as a technician solving small problems.
But now i want to adjust a program ..
An external device (depending of its working mode) gives a signal to the PLC
or it outputs is 1
or it give tree pulses end stays 1
the output is wired to a PLC input

what is the easiest way to recognize this difference in the program?
I temporaly have a solutions whit a timer and a counter but i bet there is a better way to program it ?
any help?

A timer and a counter sounds right - stay with what you've got if it works.

I think that you shouldn't try to adjust anything except after you get the proper training.

I've seen before bad things happen when unexperienced personnel try to modify things to prove they are not less than anyone .