Rockwell Automation 1794-ID2 U.MNL INCREMENTAL ENCODER - Manual (Page 18)

1–6 Overview of the Incremental Encoder Module
Publication 1794ĆUM015B-EN-P - May 2001
Count Pulses from Incremental Encoders
Ifcountermode = 1, 2 or 3, then 1, 2 or 4 edges ofthe pulse train will be counted. The count
direction (up/down) is determined by the phase difference of the input signals A and B.
Counter Mode = 1, 2 or 3
Counter Register
Logic
A
B
Up/Down
Up/Down Counting using pulses at the inputs of A and B
1 2 3 2 1
Input A
Input B
Counter Value
Counting Up Counting Down
Example 1 - Counter Mode = 1 (x1)
0
1 3 5 4 2
Input A
Input B
Counter Value
Counting Up Counting Down
Example 2 - Counter Mode = 2 (x2)
0 2 4 3 1
1 5 9 8 4
Input A
Input B
Counter Value
Counting Up Counting Down
Example 3 - Counter Mode = 3 (x4)
0 3 7 6 2 4 8 5 1 2 6 7 3
Pulse Counting Mode (001, 010. 011)