Hi,
the PT-Parameter of TON is in TIME format. TIME is a 32 bit integer, which names the time in milliseconds.
You can call the TON in your program with a separate data-block, or as a multiinstance in another FB.
Search for the adress of the PT parameter and use this adress in InTouch. Use an I/O Integer, e.g. with adress "DB1,DINT2".
Make sure that the user cannot enter a time-value of 0. With 0 ms the TON (and also TOFF) block will not let the input signal through!