11-19
11 High-speed Counters
CP1E CPU Unit Software User’s Manual(W480)
11-3 High-speed Counter
Interrupts
11
11-3-2 Present Value Comparison
Precautions for Correct UsePrecautions for Correct Use
• There are restrictions on the maximum response frequencies of the high-speed counters
when using target matching.
Use the counters for target matching under the frequencies in the following table.
If the pulse frequencies input to the high-speed counters are higher than those in the table,
count values may not agree.
For unit version 1.0
For unit version 1.1
• When using target matching, the interval between interrupts for target matches and the
interval between interrupts for the next target matches after the count direction (increment-
ing/decrementing) changing must be longer than 3 ms plus the sum of execution time for
interrupt tasks that may possibly happen at the same time.
The sum of execution time for interrupt tasks in one cycle is stored in A442. (For CPU Unit
version 1.0 or earlier, the interval must be longer than 6 ms plus the sum of execution time
for interrupt tasks that may possibly happen at the same time and the data in A442 is unsta-
ble.)
• If the input setting is set for up/down pulse inputs or differential phase inputs (×4), do not
change the direction at a high frequency when using target matching. If changing direction
at a high frequency, the interval of direction changing must be longer than 500µs.
If changing direction at a high frequency when using target matching, cycle time exceeded
error may occur.
There is no restriction when target matching is not used.
Example: Up/down pulse inputs
• Cycle time exceeded error occurs when using target matching
When using target matching, if the encoder input values change fast due to vibration, the
direction changing may be at a high frequency, cycle time exceeded error may occur as a
result. At this time, take measures to stabilize the encoder inputs or use range comparison.
Counter numbers for
target matching
Increment pulse
Pulse plus direction
Up and down pulses
Differential phase (×4)
More than 1 point 20kHz max. 5kHz max.
Enabling/Disabling
pulse outputs
Counter numbers for
target matching
Increment pulse
Pulse plus direction
Up and down pulses
Differential phase (×4)
Disabling pulse
outputs
Only one point 100kHz max. 30kHz max.
More than two points 60kHz max. 15kHz max.
Enabling pulse outputs Only one point 50kHz max. 10kHz max.
More than two points 40kHz max.
12
11 10
9
8
91011 7 6 5 6 7 8 9
Increment Pulse
Decrement Pulse
500µs min.
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