Rockwell Automation 1769-HSC Compact High Speed Counter Module - Manual (Page 24)

24 Rockwell Automation Publication 1769-UM006E-EN-P - July 2013
Chapter 2 Module Operation
Up and Down Pulses Mode Selection
In this mode, the counter channel increments on the rising edge of pulses applied
to input A and decrements on the rising edge of pulses applied to input B. When
set, the Direction Inhibit bit causes both A and B to increment. When set, the
Direction Invert bit causes B to increment and A to decrement. When the
Direction Invert and Direction Inhibit bits are both set, both A and B
decrement.
Figure 4 - Up and Down Pulse Mode (direction inhibit = 0, direction invert = 0)
TIP When both inputs transition simultaneously or near simultaneously, the
net result is no change to the count value.
Input A
Input B
Input Z
Incrementing Encoder
or Sensor
Increment Pulse
(count up)
Increment Pulse
(Input A)
Decrementing Encoder or
Sensor
Decrement Pulse
(count down)
Decrement Pulse
(Input B)
Count
Module