National Instruments E Series - Manual (Page 68)

Chapter 4 Signal Connections
DAQCard E Series User Manual 4-32  National Instruments Corporation
The CONVERT* pulses are masked off until the DAQCard generates
the STARTSCAN signal. If you are using internally generated
conversions, the first CONVERT* will appear when the onboard
sample interval counter reaches zero. If you select an external
CONVERT*, the first external pulse after STARTSCAN will generate
a conversion. The STARTSCAN pulses should be separated by at least
one scan period.
A counter on your DAQCard internally generates the STARTSCAN
signal unless you select some external source. This counter is started
by the TRIG1 signal and is stopped either by software or by the sample
counter.
Figure 4-19. STARTSCAN Output Signal Timing
t
w
= 50-100 ns
a. Start of Scan
t
off
t
off
= 10 ns minimum
Start Pulse
CONVERT*
STARTSCAN
STARTSCAN
b. Scan in Progress, Two Conversions per Scan
t
w