Measurement Computing DataShuttle - Manual (Page 120)

14-6 Digital I/O 11-12-01 DataShuttle and DynaRes
If the gate interval is one second and pulses come in at the rate of 100 per second (100 Hertz frequency),
the resolution is 1% or 1 Hertz. If the gate interval is reduced to 0.1 second to measure the frequency, the
poorer the resolution.
Many applications require timing beyond the 32 milliseconds that one counter/timer can do with the
internal 2 megahertz clock. This requires the cascading of two counter/timers as was done with CT1 and
CT2. The first counter/timer, CT1, can be used to feed as many other counter/timers as desired. You can,
for instance connect CT1 to several counter/timers, each timing different intervals. CT1 becomes a time
base at a lower frequency than the built in 2 megahertz clock.
You can measure another frequency by adding only a single counter/timer and gating it with CT2. Just
connect the additional counter/timer gate input as well as the gate input of CT3 to the output of CT2. You
can gate almost an unlimited number of additional counter/timers, using only a single counter/timer for
each frequency measurement. The only limitation is that the time interval (gate interval) is the same for all
of them.