Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 255)

Chapter 14
Using High-Speed Counter Instructions
14–5
The table that follows uses the terminology shown here 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).
The table below lists the types of high-speed counter you can choose.
High-Sp d Count r T p High-Sp d Count r Functionalit
Input Terminal Used
Pag High-Speed Counter Type High-Speed Counter Functionality
I/0 I/1 I/2 I/3
Page
Up
Up Counter operation uses a single-ended
input.
Up
↑
Not Used Not Used Not Used
1
Up
(with external reset and hold) Up Counter operation uses a single-ended
input with external reset and hold inputs.
Up
↑
Not Used Reset
↑
Hold
14–5
Pulse and direction
Bidirectional operation uses both pulse
and direction inputs.
Count
↑
Direction Not Used Not Used
Pulse and direction
(with external reset and hold)
Bidirectional operation uses both pulse
and direction inputs with external reset and
hold inputs.
Count
↑
Direction Reset
↑
Hold
14–9
Up and down
Bidirectional operation uses both up and
down inputs.
Up
↑
Down
↑
Not Used Not Used
Up and down
(with external reset and hold)
Bidirectional operation uses both up and
down pulse inputs with external reset and
hold inputs.
Up
↑
Down
↑
Reset
↑
Hold
14–10
Encoder
Bidirectional operation uses quadrature
encoder inputs.
A B Not Used Not Used
Encoder
(with external reset and hold)
Bidirectional operation uses both
quadrature encoder inputs with external
reset and hold inputs.
A B Z Hold
14–12
One difference between Up Counters and Bidirectional Counters is that for
Bidirectional Counters the accumulator and preset values are not changed by
the high-speed counter when the presets are reached. The RAC and HSL
instructions must be used for this function. The Up Counters clear the
accumulator values and re-load the high preset values when the previous
preset is reached.