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A-4
Application Restrictions
The following restrictions apply when using CJ1W-CT021 High-speed Counter Units.
When a 50-kHz noise filter is configured, External Control Inputs cannot read signals
shorter than 10 µs.
The time from signal input to resetting for External Control Inputs is 300 µs max.
The Open Gate, Close Gate, Preset Counter or Reset in device variables for CJ-
series Unit (for output) may not be executed if the CPU Unit is ON for only one task
period. Always keep them turned ON until the status changes in the corresponding
bit.
External Control Inputs may not be reflected in the status of External Inputs (n+2,
n+5) if the pulse width is extremely short.
The following are the main reasons for this:
• The signal is shorter than the CPU Unit task period.
The comparison operation stops for 1.5 ms from when the High-speed Counter
Value falls within the Upper Range Limit or Lower Range Limit for the range data.
However, the comparison does not stop for other Counters.
Consider the time that the comparison is stopped when making settings for range
data.
When the High-speed Counter Value reaches the comparison value, comparison
stops for 1.5 ms. However, comparison for other Counters does not stop.
Consider the time the comparison stops when setting Comparison Data.
I/O is not refreshed during unit initialization processing (while "*_UnitInitSta" is ON).
Note that Counter Values are not updated during this time.
At a restart or when the Controller is reset, including when the power is turned ON,
the variable *_UnitInitSta (unit initialization being processed) is ON for about 120 ms.
When any function which cannot guarantee the response time of 0.5 ms is used, the
approximate response time will be as follows:
Response time = 0.5 ms + function execution time
A Digital Input or Z phase input takes about 300 µs.
CJ-series High-speed Counter Units Operation Manual for NJ-series CPU Unit(W492)
Restriction
Appendicies
Reference
1-3-3 Input Specifications
3-4 Digital Input Functions
3-4 Digital Input Functions
4-2 Memory Allocation
3-4 Digital Input Functions
3-5-1 Range Mode
3-5-2 Comparison Mode
4-1-1 Data Flow
4-2-3 Details of Device Variables for
CJ-series Unit (for input/output)
A-3 Description of the Response
Time
A-17
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