ADLINK PCI-8258 - Manual (Page 184)

170 Motion Control Theory
4.10.3 PWM Control (Laser Control) (VAO Table Control)
4.10.3.1 Structure Overview
Laser cutting is now commonly applied in various metal,
non-metal, and composite material processing. The application is
highly associated with motion control. To meet this requirements
the VAO module is offered by your PCI-8254/8. The VAO module
enables quality cutting by controlling laser intensity with speed
information. Laser intensity is commonly controlled by pulse-width
modulation (PWM). Your PCI-8254/8 features varieties of PWM
control for specific applications.
See figure below for the operation of VAO module. The VAO
controller monitors PWM output with VAO table at different
speeds. Your PCI-8254/8 features two VAO controllers with output
channels that you can set as required. This enables it to output the
same or different PWMs in multiple channels concurrently. Each
VAO controller may switch among different VAO table to meet the
multi-level cutting requirements. Your PCI-8254/8 features eight
VAO tables, Table 0~7, to come up with corresponding PWM
settings, by interpolating composite speed among multiple axes,
for laser output intensity control. Source of speeds may come from
individual axes' command or feedback velocity where the noise
may be removed by embedded filters. The refresh frequency of
feedback speed is 1KHz now. The VAO module can work together
with the Point table.
Please set up PWM control mode and VAO table before using the
VAO module. Please set up function parameters with the VAO
parameter table. See below for descriptions and setup
procedures.