Rockwell Automation Publication 2080-UM002L-EN-E - November 2021 129
Chapter 8 Use the High-Speed Counter and Programmable Limit Switch
HSC Mode 5 – Two Input Counter (up and down) with External Reset and Hold
Blank cells = don’t care, = rising edge, = falling edge
Using the Quadrature Encoder
The Quadrature Encoder is used for determining direction of rotation and
position for rotating, such as a lathe. The Bidirectional Counter counts the
rotation of the Quadrature Encoder.
Figure 11
shows a quadrature encoder connected to inputs 0, 1, and 2. The
count direction is determined by the phase angle between A and B. If A leads B,
the counter increments. If B leads A, the counter decrements.
The counter can be reset using the Z input. The Z outputs from the encoders
typically provide one pulse per revolution.
Figure 11 - Quadrature Encoder Connected to Inputs
HSC Mode 6 – Quadrature Counter – Phased Inputs A and B
Table 28 - HSC Mode 5 Examples
Input Terminals Embedded Input 0 Embedded Input 1 Embedded Input 2 Embedded Input 3 CE Bit Comments
Function Count Direction Reset Hold
Example 1 on (1) off (0) on (1) off (0) off (0) on (1) HSC Accumulator + 1 count
Example 2 on (1) off (0) on (1) off (0) off (0) on (1) HSC Accumulator - 1 count
Example3 on (1) off (0) on (1) Hold accumulator value
Example 4 on (1) off (0) off (0) Hold accumulator value
Example 5 on (1) off (0) on (1) off (0) Hold accumulator value
Example 6 Clear accumulator (=0)
Inputs 0…11 are available for use as inputs to other functions regardless of the HSC being used.
Quadrature Encoder
A
B
Input 0
Input 1
Reverse Rotation
Forward Rotation
B
A
1
2
3
2
1
Count
Input 0
Input 1
Input 2
A
B
Z
Reset
Table 29 - HSC Mode 6 Examples
Input Terminals Embedded Input 0 Embedded Input 1 Embedded Input 2 Embedded Input 3 CE Bit Comments
Function Count A Count B Not Used Not Used
Example 1
(1)
off (0) on (1) HSC Accumulator + 1 count
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