Measurement Computing Data Translation DT9857, User Manual

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Chapter 5
100
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C/T 0 Gate input rising edge
• The signal that stops the measurement. The following signals are supported:
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A/D conversion complete
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Tachometer input falling edge
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Tachometer input rising edge
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Digital input 0 falling edge
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Digital input 0 rising edge
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Digital input 1 falling edge
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Digital input 1 rising edge
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Digital input 2 falling edge
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Digital input 2 rising edge
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Digital input 3 falling edge
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Digital input 3 rising edge
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Digital input 4 falling edge
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Digital input 4 rising edge
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Digital input 5 falling edge
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Digital input 5 rising edge
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Digital input 6 falling edge
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Digital input 6 rising edge
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Digital input 7 falling edge
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Digital input 7 rising edge
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C/T 0 Clock input falling edge
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C/T 0 Clock input rising edge
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C/T 0 Gate input falling edge
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C/T 0 Gate input rising edge
When the selected start edge is the same as the selected stop edge, the internal 48 MHz
counter starts incrementing when it detects the first start edge of the selected input signal and
stops incrementing when it detects the selected stop edge (which is the same as the start edge,
in this case); at that point, the counter stores and resets the count. The stored count is
maintained until it is read as part of the input data stream or until a new count is stored. Since
the stop edge is the same as the start edge in this case, the stop edge for the current
measurement is the start edge for the next measurement; therefore, no waveform periods are
missed. The value of the measure count depends on the input subsystem sample frequency,
described as follows:
• If the input subsystem sample frequency is faster than the selected input frequency, then
the stored measure count retains the current value when it is read by the input subsystem.