Chapter 2
Analog Input
2-46
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AI Hold Complete Event Signal
AI Hold Complete Event (ai/HoldCompleteEvent) is an output-only signal
that generates a pulse with the leading edge occurring approximately 50 to
100 ns after an A/D conversion begins. The polarity of this output is
software-selectable, but is typically configured so that a low-to-high
leading edge can clock external AI multiplexers indicating when the input
signal has been sampled and can be removed. This signal has a 400 to
500 ns pulse width and is software-enabled. Figure 2-34 shows the timing
for ai/HoldCompleteEvent.
Figure 2-34.
ai/HoldCompleteEvent Timing
External Strobe Signal
External Strobe is an output-only signal on the EXT STROBE pin that
generates either a single pulse or a sequence of eight pulses in the
hardware-strobe mode. An external device can use this signal to latch
signals or to trigger events. In the single-pulse mode, software controls the
level of External Strobe. A 10 ms and a 1.2
µ
s clock are available for
generating a sequence of eight pulses in the hardware-strobe mode.
Figure 2-35 shows the timing for the hardware-strobe mode External
Strobe signal.
Figure 2-35.
External Strobe Timing
Note
External Strobe is used for signal conditioning with SCXI and is not available for
use with NI-DAQmx.
t
w
= 400 to 500 ns
t
d
= 50 to 100 ns
ai/ConvertClock
ai/HoldCompleteEvent
t
d
t
w
t
w
= 600 ns or 5
µ
s
t
w
t
w
V
OH
V
OL
