User manual

Chapter 4 Connecting Signals
© National Instruments Corporation 4-23 NI 6034E/6035E/6036E User Manual
Figure 4-12 shows a typical pretriggered DAQ sequence. The description
for each signal shown in these figures is included later in this chapter.
Figure 4-12. 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 4-13 shows the timing for the SCANCLK signal.
Figure 4-13. SCANCLK Signal Timing
Don't Care
01231 0222
TRIG1
TRIG2
STARTSCAN
CONVERT*
Scan Counter
t
w
= 400 to 500 ns
t
d
=50to100ns
CONVERT*
SCANCLK
t
d
t
w
UM.book Page 23 Monday, May 14, 2001 10:32 AM