Counter With External Direction - Allen-Bradley 2080-IQ4 User Manual

Appendix 4 High Speed Counter – 2080-MOT-HSC
Count Pulse
(Input A)
Direction Control
(Input B)
Present Count
1
28

Counter with External Direction

Pulses on A cause the counter to increment when B is low and decrement when B
is high. When B is open or undriven, the counter will increment. See
External Direction Counting on page
Pulse External Direction Counting
Incrementing Encoder or Sensor
Sensor or Switch
2
3
A B
0 (Open or No Connection)
1
1 X (don't care)
0 X (don't care)
Two input counter (Up/Down Pulses)
Pulses on A causes the counter to increment. Pulses on B causes the counter to
decrement. Pulses may occur at any time. Note that pulses can occur very closely
(that is, much faster than plug-in scan time) that the plug-in never notices the
change in count. In such cases, both counts may be ignored (the net change being
zero anyway). In no case shall a pulse be lost. See the following diagram.
28.
Count pulse
Direction control
0
2 1
Rockwell Automation Publication 2080-UM004C-EN-E - March 2015
Pulse
INPUT A
INPUT B
INPUT Z
1 2
Change in Count Value
+1
-1
0
0