Direction of count – Rockwell Automation 1794-VHSC 1794 FLEX I/O Very High Speed Counter Module User Manual User Manual
Page 13
Rockwell Automation Publication 1794-UM010D-EN-E - July 2013
5
Overview of the Very High Speed Counter Module
Direction of Count
The module can count either up or down, depending upon the condition of the B
input for each counter. In encoder applications, the counter will increment on the
leading edge of input A, while input B determines the direction of the count.
You also have the option of X1, X2 and X4 multiplying of the input pulses. See
Figure
Phase Relationship for Forward or Reverse Directions on page 5
for the
relationships between inputs A and B for forward and reverse directions in
encoder applications.
Phase Relationship for Forward or Reverse Directions
The following paragraphs apply to both encoders and counters.
A input
B input
X1
count
X4
count
A
B
Input A
Input B
Reverse rotation
CW encoder rotation
Forward rotation
CCW encoder rotation
1
2
0
3
1
2
1
2
3
4
5
6
7
8
9
10 11 12
X2
count
1
2
3
4
5
6
7
8
9
10
11
12
0
1
2
3
4
5
6
7
8
9
10 11 12
1
2
3
4
5
6
7
8
9
10
11
12
0
Z (Store count)
Quadrature encoder
1794-VHSC
Input Z
(Gate/Reset)
45892