High Speed I/O
High Speed I/O
High Speed Counter (HSC) Functions 84
High Speed Counter 90
Pulse Width Modulation (PWM) Functions 91
HSC Pulse Output 94
In addition to the compliment of simple analog and digital I/O, the Micro OCS controller supports High Speed Count-
ing (HSC) I/O functions and may support Pulse Width Modulation (PWM) Output functions. The HSC functions
include frequency, totalizing, pulse width, and quadrature measurement.
The PWM functions include traditional PWM (with variable rate and duty) with variable acceleration and decel-
eration rates. To determine function availability, refer to the associated model’s Specification/Installation sheet
(Digital DC Input/Output sections).
Glossary of High Speed I/O Terms
Accumulator Register used to accumulate or store up a sum or count of many items or events.
Clear
A special function to zero out the value in a specific register. (Not used with Frequency or Period
Measurement.)
Disable A special function to prevent the counter from running.
Encoder A sensor or transducer for converting rotary motion or position to a series of electronic pulses
FPGA
An integrated, configurable circuit that allows the controller to be programmed to have either two
high-speed counters or four high-speed counters.
Frequency
Input
The number of times an electromagnetic signal repeats an identical cycle in a unit of time, usually
one second.
Latch (strobe)
A special function that uses a digital logic circuit to store one or more bits. A latch has a data
input, a clock input and an output. When the clock input is active, data on the input is "latched" or
stored and transferred to the output register either immediately or when the clock input goes inact-
ive. The output retains its value until the clock goes active again.
Marker
Input into the OCS that indicates a particular position. Typically, an encoder has a marker output
that represents a specific point in the rotation.
Polarity
A Polarity pull-down box is associated with each function and indicates the manner in which the
trigger happens (e.g., High level, Low Level, Falling Edge, Rising Edge).
Preload (load)
A special function used to trigger loading of a value into a register upon an event. (Not used with
Frequency or Period Measurement.)
Quadrature
A high-speed device that expresses the phase relationship between two periodic quantities of the
same period when the phase difference between them is one fourth of a period. A coupler in
which the two output signals are 90° out of phase.
Totalizer A counter that sums the total number of cycles applied to its input.
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