Contec CNT32-4MT, Руководство пользователя

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4. Functions
CNT32-4MT(LPCI)
65
Other functions
Digital filter
The digital filter is provided so that the counter works normally even when the pulse input to the counter,
phase-A/B/Z signal, or control input signal has noise. When the digital filter detects the High (or Low)
level maintained for the digital filter setting time, it outputs “High” (or “Low”) to the counter circuit.
The setting range is set by software to “unused” or 0.1
μ sec to 1.6384 msec.
Note that, since all of these digital signals are input to the internal counter through the digital filter, a
delay of the set time is required for them to be input when the digital filter is used.
Initially, the delay owing to the digital filter does not occur as it is not used by default.
* The same applies also to the LOW level.
Externally
input signal
Externally
input signal
Digital filter
Digital filter setting time
Input to the PC
Not valid Valid
Input to the PC
Figure 4.18. Digital filter
CAUTION
- The digital filter is initially disabled. (It remains disabled when left untouched.)
- The delay may be longer than the set time depending on the noise included.
- If the level changes at a frequency shorter than the set time, the level change is ignored and the input
is not counted correctly.
Timer
The timer can generate an interrupt at software-set intervals. The setting range is 1 to 6553 msec
(in 1 ms increments).