Measurements Using Two Pulse Encoders; Buffered (Sample Clock) Position Measurement - National Instruments DAQ X Series User Manual

the channel B goes low to enter the reload phase, the increment occurs first.
The reload occurs within one maximum timebase period after the reload
phase becomes true. After the reload occurs, the counter continues to count
as before. The figure illustrates channel Z reload with X4 decoding.

Measurements Using Two Pulse Encoders

The counter supports two pulse encoders that have two channels—channels
A and B.
The counter increments on each rising edge of channel A. The counter
decrements on each rising edge of channel B, as shown in Figure 7-22.
For information about connecting counter signals, refer to the
Counter/Timer Pinouts

Buffered (Sample Clock) Position Measurement

With buffered position measurement (position measurement using a
sample clock), the counter increments based on the encoding used after the
counter is armed. The value of the counter is sampled on each active edge
of a sample clock. A DMA controller transfers the sampled values to host
memory. The count values returned are the cumulative counts since the
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Ch A
Ch B
Ch Z
Max Timebase
Counter Value
5 6
Figure 7-21. Channel Z Reload with X4 Decoding
Ch A
Ch B
Counter Value 2 3
Figure 7-22. Measurements Using Two Pulse Encoders
section.
7-25
Chapter 7
7 8 9 0 1 2
A = 0
B = 0
Z = 1
4 5 4
X Series User Manual
Counters
3 4
3 4
Default