Do you mean it is a single pulse? What is the cycle time of the pulse?
PULSEWIDTH function is typically used to measure the width of the "ON" cycle of incoming input pulse with period < 3 seconds.
if it is a one-off pulse, you may be able to used an interrupt input to start a high speed timer and also capture the value of the timer when the input turns OFF. The difference is the pulse width of this single pulse but the resolution is 10ms.
For Nano-10, FMD or F-series you may start a periodic interrupt that increment a variable every 1 ms and use it as a timer source for clocking the rising edge and falling edge of the interrupt inputs. The difference is the pulse width and that has resolution of 1ms.
