Contec F&eIT Series User Manual page 33

Using the I/O Address Map
Mono-phase input
During mono-phase input, the system counts up upon the input of an UP pulse, and
counts down upon the input of a DOWN pulse. A count 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 DIR = 1 is specified.
If DIR = 0, a DOWN count commences when a phase A pulse rises, and an UP count commences
when a phase B pulse falls.
Figure 4.11.
Mono-Phase Input with Gate Control
The counter can be started/stopped according to the gate control signal that is input
together with a string of mono-phase pulses. The clear signal zero-clears the counter
value.
Mono-phase pulse
(phase A/UP)
Gate control signal
(phase B/DOWN)
Count value
* The figure above illustrates the counting operation when DIR = 1 is specified.
If DIR = 0, a DOWN count commences when the gate control signal (phase B/DOWN)
is HIGH and when a mono-phase pulse example (phase A/UP) rises; the counting stops
when the gate control signal is LOW.
Figure 4.12.
28
5
6
Example of Counting with Mono-Phase Input
6 7
Example of a Mono-Phase Input Count with Gate Control
7
8
No counting
8
6
7
9
CNT24-2(FIT)GY