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Method
1
1b
2
3
NI cDAQ-9172 User Guide and Specifications
Table 6 summarizes some of the differences in methods of measuring
frequency.
Table 6. Frequency Measurement Method Comparison
Number of
Measurements
Counters Used
1
1
1 or 2
2
For information on connecting counter signals, refer to the
Counter/Timer Routing
Position Measurement
You can use the counters to perform position measurements with
quadrature encoders or two-pulse encoders. You can measure angular
position with X1, X2, and X4 angular encoders. Linear position can be
measured with two-pulse encoders. You can choose to do a single-point
(on-demand) position measurement or a buffered (sample clock) position
measurement. You must arm a counter to begin position measurements.
Measurements Using Quadrature Encoders
The counters can perform measurements of quadrature encoders that
use X1, X2, or X4 encoding. A quadrature encoder can have up to
three channels—channels A, B, and Z.
X1 Encoding
When channel A leads channel B in a quadrature cycle, the counter
increments. When channel B leads channel A in a quadrature cycle, the
counter decrements. The amount of increments and decrements per cycle
depends on the type of encoding—X1, X2, or X4.
Measures High
Number of
Frequency
Returned
Accurately
1
Many
1
1
section.
54
Measures Low
Frequency
Signals
Signals
Accurately
Poor
Good
Fair
Good
Good
Good
Good
Default
Poor
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