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Chapter 4 Signal Connections
National Instruments Corporation 4-33 AT-MIO/AI E Series User Manual
Figure 4-14. Typical Pretriggered Acquisition
SCANCLK Signal
SCANCLK 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 analog input 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 4-15
shows the timing for the
SCANCLK signal.
Figure 4-15. SCANCLK Signal Timing
EXTSTROBE* Signal
EXTSTROBE* is an output-only signal 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 the
Don't Care
01231 0222
TRIG1
TRIG2
STARTSCAN
CONVERT*
Scan Counter
t
w
t
w
= 400 to 500 ns
t
d
= 50 to 100 ns
t
d
CONVERT*
SCANCLK