National Instruments NI 6711 User Manual

Also see for DAQCard-6715: User manual User manual

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National Instruments NI 6711 User Manual Manual pdf 61 page image

Chapter 5 Counters© National Instruments Corporation 5-7 Analog Output Series User ManualCounter 1 Source SignalYou can select any PFI as well as many other internal signals as theCounter 1 Source (Ctr1Source) signal. The Ctr1Source signal is configuredin edge-detection mode on either rising or falling edge. The selected edgeof the Ctr1Source signal increments and decrements the counter valuedepending on the application the counter is performing.You can export the Counter 1 signal to the PFI 3/CTR 1 SOURCE pin, evenif another PFI is inputting the Ctr1Source signal. This output is set tohigh-impedance at startup.Figure 5-7 shows the timing requirements for the Ctr1Source signal.Figure 5-7. Ctr1Source Timing RequirementsThe maximum allowed frequency is 20 MHz, with a minimum pulse widthof 10 ns high or low. There is no minimum frequency.For most applications, unless you select an external source, the20MHzTimebase signal or the 100kHzTimebase signal generates theCtr1Source signal.Counter 1 Gate SignalYou can select any PFI as well as many other internal signals like theCounter 1 Gate (Ctr1Gate) signal. The Ctr1Gate signal is configured inedge-detection or level-detection mode depending on the applicationperformed by the counter. The gate signal can perform many differentoperations including starting and stopping the counter, generatinginterrupts, and saving the counter contents.You can export the gate signal connected to Counter 1 to the PFI 4/CTR 1GATE pin, even if another PFI is inputting the Ctr1Gate signal. This outputis set to high-impedance at startup.tw = 10 ns minimumtp = 50 ns minimumtptw tw