National Instruments NI USB-621x User Manual

Chapter 9 Counters
NI USB-621x User Manual 9-16 ni.com
Figure 9-15 shows a quadrature cycle and the resulting increments and
decrements for X1 encoding. When channel A leads channel B, the
increment occurs on the rising edge of channel A. When channel B leads
channel A, the decrement occurs on the falling edge of channel A.
Figure 9-15. X1 Encoding
X2 Encoding
The same behavior holds for X2 encoding except the counter increments or
decrements on each edge of channel A, depending on which channel leads
the other. Each cycle results in two increments or decrements, as shown in
Figure 9-16.
Figure 9-16. X2 Encoding
X4 Encoding
Similarly, the counter increments or decrements on each edge of
channels A and B for X4 encoding. Whether the counter increments or
decrements depends on which channel leads the other. Each cycle results in
four increments or decrements, as shown in Figure 9-17.
Figure 9-17. X4 Encoding
Ch A
Ch B
Counter Value
7
7
6
5
5
6
Ch A
Ch B
Counter Value
56 8
9
7
5
6
8
9
7
Ch A
Ch B
Counter Value 5 6 8 9 10 1011 1112 1213 137
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National Instruments NI USB-621x Specifications

General

Brand	National Instruments
Model	NI USB-621x
Category	Computer Hardware
Language	English