Chapter 4 Signal ConnectionsPCI-MIO E Series User Manual4-28 ©National Instruments CorporationFigure 4-12. Typical Pretriggered AcquisitionSCANCLK SignalSCANCLK is an output-only signal that generates a pulse with theleading edge occurring approximately 50 to 100 ns after an A/Dconversion begins. The polarity of this output is software-selectable butis typically configured so that a low-to-high leading edge can clockexternal analog input multiplexers indicating when the input signal hasbeen sampled and can be removed. This signal has a 400 to 500 ns pulsewidth and is software enabled. Figure 4-13 shows the timing for theSCANCLK signal.Figure 4-13. SCANCLK Signal TimingDon't Care0 123 1 02 2 2TRIG1TRIG2STARTSCANCONVERT*Scan Countertwtw = 400 to 500 nstd = 50 to 100 nstdCONVERT*SCANCLK
