National Instruments M Series - Page 366

Appendix B Timing Diagrams
© National Instruments Corporation B-43 M Series User Manual
Gating Modes
Gating mode refers to how the counter/timer uses the Gate input. Some
timing operations depend on the gating mode. Depending on the
application, the counter/timers either level gating mode or edge gating
mode.
In NI-DAQmx, the counter/timers use level gating mode for the following
measurements:
• Edge counting
• Pulse width measurements
• Two-signal edge separation measurements
All other measurements use edge gating mode.
Quadrature and Two Pulse Encoder Timing
Counter n A, Counter n B, and Counter n Z, described in the Counter n A,
Counter n B, and Counter n Z Signals section of Chapter 7, Counters, are
used in position measurements using quadrature encoder or two-pulse
encoder counting modes. Table B-35 shows the timing requirements for
these signals.
Figure B-51. Quadrature and Two Pulse Encoder Timing Diagrams
Counter n A
t
15
Counter n Z
t
15
t
14
Counter n B
t
17
t
17
t
16
t
19
t
18
t
20
t
18