Measuring time in TwinCAT

[arbitart]

Hi,
I'm looking to measure the time between an input and an output in twinCAT using structured text. How would I go about doing so?

I've seen the function blocks such as getsystemtime can track the passage of time but I am confused as to what to the outputs it gives refer to.

Thanks

 

[shooter]

use now()
however it is impossible to check how long it takes when an input gets true, and then measure the time until the output gets on, this is separate process.
however you can measure how long your program takes, by putting
usedtime:= now()-oldtime;
oldtime:=now()