I/O Ports and Registers
CNT24-4(PCI)
40
Counter Operation Mode
2-phase input
The 2-phase input inputs two different pulses when there is 90
degree difference between the A-phase (forward signal) and the
B-phase (following signal).
Inputting a Z-phase pulse clears the counter if there is a Z-phase
(base position signal).
A-phase
(A-phase/UP)
B-phase
(B-phase/DOWN)
Z-phase
(Z-phase/CLR)
Counting
0
1
2
Figure 4.4. Counting Example with 2-phase Input
Single-phase input
For a single-phase input, the counter counts up with an UP pulse
and counts down with a DOWN pulse. If UP and DOWN pulses
occur at the same time or both pulses are LOW, the counter will not
count properly.
UP pulse
(A-phase/UP)
DOWN pulse
(B-phase/DOWN)
Counting
6
7
8
5
6
7
Figure 4.5. Single-phase Counting Example
Note!
This is a counting operation when DIR=1. If DIR=0, the counter
counts down with the rising edge of an UP pulse and counts up with
the rising edge of a DOWN pulse.
