Novanta f201, Руководство пользователя

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CONTROLLING LASER POWER PAGE | 58
Command signal
The modulated Command signal applied between Pin 9, PWM Input, and Pin 1, PWM Return, of the User.
I/O connector on the F201 laser f201 laser 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 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 μ s. 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 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. Figure below
illustrates PWM Command signal parameters while the table below lists PWM signal specifications.
Figure 4-4 PWM Command signal waveform.
F201 laser’s User 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. Table below provides
minimum, maximum, and nominal PWM signal specifications.
Warning: Serious Personal Injury
Always use shielded cable when connecting your PWM Command signal source to PWM Input/PWM
Return inputs. In electrically noisy environments, long lengths of unshielded wire act like an antenna
and may generate enough voltage to trigger un-commanded lasing.