Measurement-computing StrainBook/616 Manual do Utilizador descarregar pdf (Página 100)

8-4 Digital I/O, TTL Trigger, and External Clock 977794 StrainBook/616

StrainBooks have a 32-bit interna

l counter that calculates and reports the external clock’s period. The

counter can be read with each scan of the analog data. This is often beneficial in later analysis, when there

is a need to correlate physical phenomena with speed.

The counter channel actually consists of two independent channel

s (CtrLo and CtrHi). These can be turned

“On” in the Channel Configuration Spreadsheet. When enabled, the low (CtrLo), then high (CtrHi) words

of the counter will be configured in each scan. Note that the spreadsheet’s Units column can be used to

view a predefined period in units of seconds, ms, or µsec.

WaveView can be configured to read only the low word of t

he counter data (CtrLo:“On,” CtrHi: “Off”).

This decreases the minimum scan period by 1 usec. This LoCtr only option can be used only when the

external clock frequency is greater than 305 Hz (20,000,000 MHz / 65536]. Note that WaveView does not

enforce this.

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Measurement-computing StrainBook/616 Manual do Utilizador Página 100