Rockwell Automation 1769-HSC Compact High Speed Counter Module - Manual (Page 22)

22 Rockwell Automation Publication 1769-UM006E-EN-P - July 2013
Chapter 2 Module Operation
Pulse/External Direction Mode Selection
In this mode, the B input controls the direction of the counter, as shown in
Figure 3. If the B input is low (0), the counter increments on the rising edges of
input A. If the input B is high (1), the counter decrements on the rising edges of
input A.
Figure 3 - Pulse/External Direction Mode (direction inhibit = 0, direction invert = 0)
TIP Two Output Control bits let you modify the operation of the B input from
your control program or during configuration. The Direction Inhibit bit,
when set (1), disables the operation of the B input.
The Direction Invert bit, when set (1), reverses the operation of the
B input, but only if the Direction Inhibit bit is not set. If the Direction
Inhibit bit is set, then the Direction Invert bit controls counter direction:
• When the Direction Inhibit bit is set (1) and Direction Invert = 0, count
direction is up (forward).
•
When the Direction Inhibit bit is set (1) and Direction Invert = 1, count
direction is down (reversed).
Input A
Encoder or Sensor
Count Pulse
Count Pulse
Count
Input B
Input Z
Direction Control
Sensor or Switch
Direction Control
High = Decrement
Low = Increment