Chapter 4 Connecting Signals© National Instruments Corporation 4-21 NI 6013/6014 User ManualAs an input, each PFI pin can be individually configured for edge or leveldetection and for polarity selection. You can use the polarity selection forany of the timing signals, but the edge or level detection depends upon theparticular timing signal being controlled. The detection requirements foreach timing signal are listed within the section that discusses that individualsignal.In edge-detection mode, the minimum pulse width required is 10 ns. Thisapplies for both rising-edge and falling-edge polarity settings. There is nomaximum pulse-width requirement in edge-detect mode.In level-detection mode, there are no minimum or maximum pulse-widthrequirements imposed by the PFIs themselves, but there may be limitsimposed by the particular timing signal being controlled. Theserequirements are listed later in this chapter.DAQ Timing ConnectionsThe DAQ timing signals are TRIG1, TRIG2, STARTSCAN, CONVERT*,AIGATE, SISOURCE, SCANCLK, and EXTSTROBE*.Posttriggered data acquisition allows you to view only data that is acquiredafter a trigger event is received. A typical posttriggered DAQ sequence isshown in Figure 4-11.Figure 4-11. Typical Posttriggered Acquisition13 04 2TRIG1STARTSCANCONVERT*Scan Counter
