Rockwell Automation 1769-HSC Compact High Speed Counter Module - Manual (Page 23)

Rockwell Automation Publication 1769-UM006E-EN-P - July 2013 23
Module Operation Chapter 2
See Direction Inhibit and Direction Invert Output Control Bits on page 21 for
more information.
Pulse/Internal Direction Mode Selection
When the Pulse/Internal Direction mode is selected, the status of the Direction
Invert bit, as controlled by the user program, determines the direction of the
counter. The counter increments on the rising edge of the module’s A input
when the Direction Invert bit is reset (0). The counter decrements on the rising
edge of the A input when the Direction Invert bit is set (1).
Table 2 - Pulse External Direction Counting
Direction
Inhibit Bit Direction
Invert Bit Input A (count) Input B (direction) Change in
Count Value
0 0

0 or open 1

1 -1
0, 1,

Don’t care 0
0 1

0 or open -1

1 1
0, 1,

Don’t care 0
1 0

0 or open 1

1 1
0, 1,

Don’t care 0
1 1

0 or open -1

1 -1
0, 1,

Don’t care 0
Table 3 - Pulse Internal Direction Counting - Counters 0 and 1
Direction
Inhibit Bit Direction
Invert Bit Input A (count) Input B Change in Count
Value
Don’t care 0

Don’t care 1
0, 1,

Don’t care 0
Don’t care 1

Don’t care -1
0, 1,

Don’t care 0
Table 4 - Pulse Internal Direction Counting - Counters 2 and 3
Direction
Inhibit Bit Direction
Invert Bit Input A Input B (count) Change in Count
Value
Don’t care 0 Don’t care

1
Don’t care 0, 1,

0
Don’t care 1 Don’t care  -1
Don’t care 0, 1,

0