National Instruments NI 6120 用户手册
Chapter 4
Connecting Signals
© National Instruments Corporation
4-25
Figure 4-19. STARTSCAN Output Signal Timing
The CONVERT* pulses are masked off until the device generates
STARTSCAN. 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. STARTSCAN pulses should be
separated by at least one scan period.
STARTSCAN. 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. STARTSCAN pulses should be
separated by at least one scan period.
A counter on the NI 6115/6120 internally generates STARTSCAN unless
you select some external source. This counter is started by the TRIG1
signal and is stopped by either software or the sample counter.
you select some external source. This counter is started by the TRIG1
signal and is stopped by either software or 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 signal AIGATE or
the 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 signal AIGATE or
the software command register gate.
t
w
t
w
= 25 – 50ns
a. Start of Scan
b. Scan in Progress, Two Conversions per Scan
Start Pulse
CONVERT*
STARTSCAN
t
off
= 10 ns minimum
t
off