Contec F&eIT Series User Manual page 60

Function
This item sets a counter function.
- Mono-phase counter
In the case of the mono-phase counter, the system counts up upon the input of an UP
pulse, and counts down upon the input of a DOWN pulse. The counting process
fails if UP and DOWN pulses occur simultaneously or both pulses happen to be
LOW.
UP pulse
(phase A/UP)
DOWN pulse
(phase B/DOWN)
Count value
* The figure above illustrates the counting operation when a count direction = 01h is specified.
If count direction = 00h, a DOWN count commences when phase A pulse rises, and an UP count
commences when a phase B pulse rises.
Figure 5.2.
- 2-phase counter
The 2-phase counter counts the 2-phase pulse inputs of phases A and B that have a
90° phase difference. This option is principally used to count pulse inputs from an
incremental rotary encoder.
If both phases A and B change simultaneously, the condition is treated as an input
error and cannot successfully be counted.
Phase A
(phase A/UP)
Phase B
(phase B/DOWN)
Phase Z
(phase Z/CLR)
Count value
* The figure above illustrates the counting operation when a count direction = 01h is specified.
If count direction = 00h, a DOWN count commences when phase A rises.
Figure 5.3.
CNT24-2(FIT)GY
00h: Mono-phase counter
01h: 2-phase counter
02h: Mono-phase counter with gate control
5
6
Mono-Phase Counter
0
2-Phase Counter
Using the Memory Address Map
7 8
1 2
6
7
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