Rockwell Automation Allen-Bradley Micro820

Rockwell Automation Publication 2080-UM002M-EN-E - April 2022 191
Chapter 9 Use the High-Speed Counter and Programmable Limit Switch
HSC Mode 4 – Two Input Counter (up and down)
Blank cells = don’t care,  = rising edge,  = falling edge
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 16
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.
Inputs 0…11 are available for use as inputs to other functions
regardless of the HSC being used.
Table 34 - HSC Mode 4 Examples
Input Terminals Embedded Input 0 Embedded Input 1 Embedded Input 2 Embedded Input 3 CE Bit Comments
Function Count Up Count Down Not Used Not Used
Example 1  on (1)  off (0) on (1) HSC Accumulator + 1 count
Example 2 on (1)  off (0)  on (1) HSC Accumulator - 1 count
Example3 off (0) Hold accumulator value
Inputs 0 through 11 are available for use as inputs to other functions regardless of the HSC being used.
Table 35 - 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.