Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 273)

Execution Times
(µ
sec
)
when:
True False
12.00 7.00
Ladder representation:
C5:0
UA
)
)
Chapter 14
Using High-Speed Counter Instructions
14–23
When an OUT bit instruction is addressed for the high-speed counter (C0)
UA bit, the value in the hardware accumulator is written to the value in the
image accumulator (C0.ACC). This provides you with real-time access to
the hardware accumulator value. This is in addition to the automatic transfer
from the hardware accumulator to the image accumulator that occurs each
time the HSC instruction is evaluated.
Entering the Instruction
You enter the instruction from within the program monitor functional area.
P 0 0 0
C 0 0 / U A 0
Operation
This instruction transfers the hardware accumulator to the instruction
accumulator. When the OUT instruction is executed true, the hardware
accumulator is loaded to the instruction image accumulator (C0.ACC).
Once initialized, the HSC instruction retains its previous state when going
through a mode change or power cycle. This means that the HSC
Accumulator (C0.ACC) and High Preset values are retained. Outputs under
the direct control of the HSC also retain their previous state. The Low Preset
Reached and High Preset Reached bits (C0/LP and C0/HP) are also retained.
They are examined by the HSC instruction during the high-speed counter’s
first true evaluation in the RRUN mode to differentiate a retentive RRUN
mode entry from an external or initial Accumulator (C0.ACC) modification.
At the first true HSC instruction execution after going to run, the Low Preset
is initialized to –32,768 and the output mask and high and low output
patterns are initialized to zero. Use the HSL instruction during the first pass
to restore any values necessary for your application.
You can modify the behavior of the high-speed counter at RRUN mode entry
by adjusting the HSC parameters prior to the first true execution of the HSC
instruction. The following example ladder rungs and instruction lists
demonstrate different ways to adjust the HSC parameters.
Update High-Speed Counter
Image Accumulator (OUT)
1
OUT
To enter the OUT instruction, press:
What Happens to the HSC
When Going to RRUN Mode