Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 220)

Preface MicroLogix 1000 Programmable Controllers User Manual
12–6
High-Speed Counter (HSC)
Use this instruction to configure the high-speed counter. Only one HSC instruction
can be used in a program. The high-speed counter is not operational until the first
true execution of the HSC instruction. When the HSC rung is false, the high-speed
counter is disabled from counting, but all other HSC features are operational.
The Counter address of the HSC instruction is fixed at C5:0.
After the HSC is configured, the image accumulator (C5:0.ACC) is updated with the
current hardware accumulator value every time the HSC instruction is evaluated as
true or false.
Entering Parameters
Enter the following parameters when programming this instruction:
•
Type indicates the counter selected. Refer to page 12–7 for making your
high-speed counter selection. Each type is available with reset and hold
functionality.
•
High Preset is the accumulated value that triggers a user-specified action such
as updating outputs or generating a high-speed counter interrupt.
•
Accumulator is the number of accumulated counts.
The following terminology is used in the following table to indicate the status of
counting:
•
Up ↑ – increments by 1 when the input energizes (edge).
•
Down
↑
– decrements by 1 when the input energizes (edge).
•
Reset
↑
– resets the accumulator to zero when the input energizes (edge).
•
Hold – disables the high-speed counter from counting while the input is
energized (level).
•
Count – increments or decrements by 1 when the input energizes (edge).
•
Direction – allows up counts when the input is de-energized and down counts
while the input is energized (level).
•
A – input pulse in an incremental (quadrature) encoder (edge/level).
•
B – input pulse in an incremental (quadrature) encoder (edge/level).
•
Z – reset pulse in an incremental (quadrature) encoder (edge/level).
•
↑
– the signal is active on the rising edge only (off to on).
Execution Times
(µ
sec
)
when:
True False
21.00 21.00
HSC
HIGH SPEED COUNTER
Type
Counter
C5:0
High Preset 0
Accum 0
(CD)
(CU)
(DN)