© National Instruments Corporation 55 NI cDAQ-9172 User Guide and Specifications
Figure2 8 shows a quadrature cycle and the resulting increments and
decrements for X1 encoding. When channelA leads channel B, the
increment occurs on the rising edge of channelA. W hen channel B leads
channelA, the decrement occurs on the falling edge of channel A.
Figure 28. 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 29.
Figure 29. X2 Encoding
X4 Encoding
The counter increments or decrements similarly on each edge of
channelsA 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 30.
Figure 30. X4 Encoding
Ch A
Ch B
Counter Value 7 7 6 5
5 6
Ch A
Ch B
Counter Value 5 6 8 9
7 5
6
8
9 7
Ch A
Ch B
Counter Value 5 6 8 9 10 10 11 11 12 12 13 13 7 5 6 8 7 9