NI DAQ 6052E, Руководство пользователя

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Chapter 4 Connecting the Signals
NI 6052E User Manual 4-34 ni.com
Either the 20 MHz or 100 kHz internal timebase generates SISOURCE
unless you select an external source. Figure 4-25 shows the timing
requirements for SISOURCE.
Figure 4-25. SISOURCE Signal Timing
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 configurable, but the polarity 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 4-26 shows the timing for SCANCLK.
Note
The polarity of SCANCLK is not software selectable when programmed using
NI-DAQ. It is a positive polarity pulse.
Figure 4-26. SCANCLK Signal Timing
t
w
= 23 ns minimum
t
p
= 50 ns minimum
t
w
t
w
t
p
t
w
= 400 to 500 ns
t
d
= 50 to 100 ns
CONVERT*
SCANCLK
t
d
t
w