National Instruments Corporation DAQCard-500 User Manual page 36

Theory of Operation Chapter 4
Each counter has a clock input pin, a gate input pin, and an output pin labeled CLK, GATE, and
OUT, respectively. The MSM82C54 counters are numbered zero through two, and their GATE,
CLK, and OUT pins are labeled GATE N, CLK N, and OUT N, where N is the counter number.
DAQCard-500 User Manual 4-8 © National Instruments Corporation