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Chapter 4
Connecting Signals
© National Instruments Corporation
4-37
Figure 4-20. STARTSCAN Output Signal Timing
The CONVERT* pulses are masked off until the device generates the
STARTSCAN signal. If you are using internally generated conversions,
the first CONVERT* appears when the onboard sample interval counter
reaches zero. If you select an external CONVERT*, the first external pulse
after STARTSCAN generates a conversion. The STARTSCAN pulses
should be separated by at least one scan period.
STARTSCAN signal. If you are using internally generated conversions,
the first CONVERT* appears when the onboard sample interval counter
reaches zero. If you select an external CONVERT*, the first external pulse
after STARTSCAN generates a conversion. The STARTSCAN pulses
should be separated by at least one scan period.
A counter on the AT E Series device 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.
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.
Scans generated by either an internal or external STARTSCAN signal are
inhibited unless they occur within a DAQ sequence. Scans occurring within
a DAQ sequence may be gated by either the hardware (AIGATE) signal or
software command register gate.
inhibited unless they occur within a DAQ sequence. Scans occurring within
a DAQ sequence may be gated by either the hardware (AIGATE) signal or
software command register gate.
STARTSCAN
a. Start of Scan
t
w
= 50 to 100 ns
t
w
Start Pulse
CONVERT*
STARTSCAN
b. Scan in Progress, Two Conversions per Scan
t
off
= 10 ns minimum
t
off