Figure 4-5 Pwm Command Signal Waveform - Novanta vi30 User Manual

OPERATING MODES PAGE | 42
Command signal
The modulated Command signal applied between Pin 1, PWM Positive, and Pin 6, PWM Negative, on
either interface connector has three basic parameters: signal amplitude, base frequency, and PWM duty
cycle. By changing these parameters, you can command the beam to perform a variety of marking,
cutting, welding, or drilling operations.
The first Command signal parameter, signal amplitude, is a square wave that is either logic low—
corresponding to laser beam off, or logic high—corresponding to beam on. The laser off voltage,
typically 0 V, can range from 0.0 V to +0.8 VDC while the laser on voltage, typically 5 V, can range from
+3.5 V to +6.7 VDC.
Base frequency, the second parameter, is the repetition rate of the PWM input signal. The standard base
frequency is 5 kHz, which has a period of 200 μs. Maximum PWM frequency is 100 kHz.
The third Command signal parameter, PWM duty cycle, is the percentage of the period that the
Command signal is high. If the Command signal's amplitude (at 5 kHz) is high for 100 μs and low for 100
μs, it has a 50% duty cycle; if the amplitude is high for 190 μs and low for 10 μs, it has a 95% duty cycle.
The following figure illustrates PWM Command signal parameters while the following table lists PWM
signal specifications

Figure 4-5 PWM Command signal waveform

The vi30/40's DB-9 I/O PWM input consists of a high-speed optoisolator LED with a forward voltage
drop (Vf) of 1.5 VDC. The PWM input frequency can range from DC (0 Hz) to 100 kHz. The following
table below provides minimum, maximum, and nominal PWM signal specifications.