Measurement-computing CIO-DAS-TEMP Instrukcja Użytkownika Pobierz pdf (Strona 12)

Generally, the choice of gate time is a matter of factoring the desired resolution against the time the

actual measurement takes.

Multiple Channels:

When scanning over multiple channels, the software must explicitly select the next channel in the scan

and start a new conversion. Once the next channel is selected, enough time must be allowed for the new

channel’s current to propagate through the multiplexers and Current-to-Voltage Converter to settle at the

Voltage-to-Frequency converter input. T his is most easily done by doing an extra, or ‘dummy’

conversion, waiting for it to complete and then starting the ‘real’ conversion. Thus, if a gate time of

0.0166 seconds is chosen, the maximum scan rate will be:

Scan Rate = 1 / 2 x [gate time]

= 1 / 2 x [0.0166 seconds]

= 30 samples per second

The following table can be used to select the Gate Count based on either desired maximum sampling rate

or desired resolution.

400Hz0.1 °C0.0025 sec5,000200 samples / sec

50Hz0.0125 °C0.02 sec40,00025 samples / sec

60Hz0.015 °C0.01 sec33,33330 samples / sec

Line Frequency

Rejection

ResolutionGate TimeGate Count

Required

Desire Max Sample

Rate

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 18 19 20

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Measurement-computing CIO-DAS-TEMP Instrukcja Użytkownika Strona 12