User manual

Chapter 3 Software Overview
© National Instruments Corporation 3-89 NI-DAQ User Manual for PC Compatibles
For 32-bit counting, use two counters. For 48-bit counting, use three
counters, and so on. The counter configurations for concatenated event
counting are as follows:
• Low-order counter configuration
gateMode—either level gating or no gating
edgeMode—any value
outType—TC pulse output type
outPolarity—positive polarity
timebase—any value
cont =1—continuous counting
• Intermediate counter configuration
edgeMode—count rising edges (indicates that the low-order counter
rolled over)
gateMode—no gating
outType—TC pulse output type
outPolarity—positive polarity
timebase =0—counts lower order counter output
cont =1—continuous counting
• High-order counter configuration
edgeMode—count rising edges (indicates that the low-order counter
rolled over)
gateMode—no gating
outType—TC-toggled output type (for proper overflow detection)
outPolarity—positive polarity
timebase =0—counts lower order counter output
cont =0—counter stops on overflow
Period and Continuous Pulse-Width Measurement
Applications
With the proper use of
CTR_Config
,
CTR_Period
, and
CTR_EvRead
,
you can configure a counter to make period or continuous pulse-width
measurements.
To make a period measurement, call
CTR_Config
with gateMode set
to either rising or falling edge-triggered gating (3 or 4). With rising
edge-triggered gating, a counter can measure the time interval