Rockwell Automation 2080 Micro800 Digital and Analog Plug-in Modules - Manual (Page 36)

28 Rockwell Automation Publication 2080-UM004B-EN-E - December 2013
Appendix 4 High Speed Counter – 2080-MOT-HSC
Pulse External Direction Counting
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.
INPUT A
INPUT B
INPUT Z
Direction control
Count pulse
Incrementing Encoder or Sensor
Sensor or Switch
Count Pulse
(Input A)
Direction Control
(Input B)
Present Count 1 2 3 2 1 0 1 2
A B Change in Count Value
0 (Open or No Connection) +1
1 -1
1 X (don’t care) 0
0 X (don’t care) 0