Specifications

Configuring a High-Speed Counter Hardware Configuration
46 VisiLogic: Getting Started
Acceleration and Deceleration
If your application
requires
acceleration/decelerat
ion as is shown in the
accompanying figure,
you can control the
speed of movement
via the Ladder
application. To see
how, check the
sample application
Stepper Control.
Configuring a High-Speed Counter
Certain digital inputs on both Snap-in I/O and I/O Expansion modules can be
used as high-speed counters in the following modes:
High-Speed counter
High-Speed counter with Reset
Shaft encoder
Frequency Measurer
Note
•
When yo
u select High
-
Speed Counter with Reset, the controller uses
an additional input for reset; shaft encoders also require the use of
two inputs.
High-speed counters are built into the hardware, you define them as part of
the controller's hardware configuration by first selecting the counter type and
then linking it to an operand that contains the counter value.
Compare Functions and Counter Values
The high-speed counter value is read once during every program scan. For this
reason, do not use the Equal (=) function together with high-speed counter
values. If the counter does not reach the value required by the Equal function
during the actual program scan, the function cannot register that the value has
been reached. Use functions Greater Than Or Equal To ( G) and Lesser Than
Or Equal To ( H).
Configuring a High-speed Output (PWM)
You can use certain outputs as High-speed Outputs (HSO) via PWM (Pulse
Width Modulation). When you select a High Speed Output in the Hardware, the
Select Operand and Address dialog box appears three successive times,
allowing you to link operands for the following values:
Duty Cycle
The ratio of the "on" period of a cycle to the total cycle period. This value
may be from 0-1000, and is expressed as a percentage.