Rockwell Automation 1756-HSC ControlLogix High Speed Counter Module - Manual (Page 19)

Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
Counter Modes 19
Counter Mode
This is the 1756-HSC module’s default operational mode that counts incoming
pulses using input A. You can control the starting and ending points of the
accumulated count depending on how you have configured the module.
In the Counter mode, the count increases or decreases based on the state of
input B, which can be a random signal. If input B is high, the counter will
count down. If input B is low or floating (that is, not connected to a voltage
source), the counter counts up. Counting is done on the leading-edge of
input A.
Input Z is used in Counter mode only if a Store Count mode is enabled.
See
page 23 for details on the Storage modes.
Counter Mode
Input B Direction of Counter
High Down
Low or floating (not connected) Up
Single-phase Pulse Generator
Count Up Count Down
1756-HSC Module
Increment/Decrement Count
Input A
Input B
Input A
Input B
+
–
... 1 2 3 0 1 2
41688
Accumulated Count
in Present Value Tag
Positive Frequency Negative Frequency
Directional Frequency
in Totalizer Tag
Input Z (optional)
Pulse Count
...