SmartAXIS Touch User's Manual 3-77
4 Special Functions
3
Project
4.10 Frequency Measurement
This section describes frequency measurement, which measures the input frequency.
●
Feature Description
These input pulses are processed in hardware, so frequencies can be measured with no relation to the scan time.
Groups that do not use frequency measurement can be used as normal inputs, high-speed counters, catch input, or
interrupt input. The measurement results are stored in special data registers and being updated with each scan.
●
Function Specification
The Touch inputs can be configured as normal input, high-speed counters, catch input, interrupt input, and frequency
measurement. To use frequency measurement, specify the relevant group as Frequency Measurement in
Function Area Settings tab.
The frequency measurement results are stored in the following special data registers. (Read-only)
Any one of Groups 2, 3, 4, or 5 can be freely set.
Inputs I6 and I7 cannot be used for frequency measurement.
Group
12345
External Input
I0 I2 I3 I4 I5
Frequency
measurement
value (32 bits)
Upper
word
– D8056 D8068 D8134 D8140
Lower
word
– D8057 D8069 D8135 D8141
Frequency measurement
range
200Hz to 10kHz
Measurement error
Less than ±1%
(Truncated after the decimal point)
Calculation cycle Each scan time
If the input pulse cycle is longer than the scan time, the measurement results are updated at pulse cycle + 1
scan time.
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