To measure velocity (for example rotational speed of a shaft) with a counter you must have a signal proportional to speed, squared and in TTL standard to input to the counter of 6070E. A good example of it is an encoder; for other devices you should consider adding some conditioning devices to achieve the correct shape and potential from your input signal.
Once the signal is suitable for 6070E inputs, you can look at Examples\Daq\Ctr\STCSinglePeriodMeasure or STCSingleBufPeriodMeasure projects for an example of how to measure the period of a signal.
Speed (in rpm) is obtained from period measure by the following formula:
TimeBase / PeriodMeasured * 60.0 / PulsesPerTurn
Where:
TimeBase is the timebase used to count period
PeriodMeasured is the
result of the counter measure
PulsesPerTurn is the number of pulses per round of the encoder or other transducer
In case you need to measure a different phenomenon (for example linear speed of an object) you still need a periodic signal proportional to speed, and must accomodate the preceding formula to the characteristics of the phenomenon.
