Chapter 4
Connecting Signals
4-32
ni.com
depends upon the particular timing signal being controlled. The detection
requirements for each timing signal are listed within the section that
discusses that individual signal.
In edge-detection mode, the minimum pulse width required is 10 ns. This
applies for both rising-edge and falling-edge polarity settings. There is no
maximum pulse-width requirement in edge-detect mode.
In level-detection mode, there are no minimum or maximum pulse-width
requirements imposed by the PFIs themselves, but there may be limits
imposed by the particular timing signal being controlled. These
requirements are listed later in this chapter.
DAQ Timing Connections
The DAQ timing signals are TRIG1, TRIG2, STARTSCAN, CONVERT*,
AIGATE, SISOURCE, SCANCLK, and EXTSTROBE*.
Posttriggered DAQ allows you to view only data that is acquired after a
trigger event is received. A typical posttriggered DAQ sequence is shown
in Figure 4-13. Pretriggered DAQ allows you to view data that is acquired
before the trigger of interest in addition to data acquired after the trigger.
Figure 4-14 shows a typical pretriggered DAQ sequence. The description
for each signal shown in these figures is included later in this chapter.
Figure 4-13.
Typical Posttriggered Acquisition
1
3
0
4
2
TRIG1
STARTSCAN
CONVERT*
Scan Counter
