Novanta v30, Руководство пользователя, Страница: 48 / 101

CONTROLLING LASER POWER PAGE | 48
OEM v30 lasers are designed to operate at Command signal base frequencies up to 100 kHz; however,
the choice of PWM frequency depends on the user’s specific application. In the majority of laser applica-
tions, the UC-2000’s default Command signal frequency of 5 kHz has proven to work well. For high-
speed motion applications that cannot tolerate any ripple in the optical beam response but still need
adjustable power levels, we recommend the use of higher PWM frequencies, up to 100 kHz maximum.
Figure 3-2 Representative v30 waveforms
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—corre-
sponding 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
μ s. Maximum PWM frequency is 100 kHz.
The third Command signal parameter, PWM duty cycle, is the percentage of the period that the Com-
mand signal is high. If the Command signal’s amplitude (at 5 kHz) is high for 100
μ
s and low for 100
μ
s, it
has a 50% duty cycle; if the amplitude is high for 190 μ s and low for 10 μ s, it has a 95% duty cycle. The
Warning: Serious Personal Injury
Always use shielded cable when connecting your PWM Command signal source to PWM
Positive/PWM Negative inputs. In electrically-noisy environments, long lengths of unshielded wire act
like an antenna and may generate enough voltage to trigger uncommand lasing.