Campbell Scientific SDM-IO16 16-Channel Input/Output Expansion Module - Manual (Page 10)

SDM-IO16 16 Channel Input/Output Expansion Module
Minimum frequency: a frequency of 0 Hz is measured if there are
less than two high-to-low signal transitions in
the measurement interval.
Minimum pulse width: a pulse must stay high or low for a minimum
of 244
μsec for a change of state or pulse to be
counted.
Switch debounce timing: with the default settings a switch between the
input and G must remain closed for 3.17 msec
and then remain open for 3.17 msec, to be
counted as a closure2. The debounce time can
be changed from the user program.
Accuracy: internal clock accuracy ±0.01% (worst case)
over the standard temperature range of -25 to
+50
°C. See also Appendix A for a discussion
on frequency resolution.
Duty cycle resolution: this depends on frequency and measurement
interval - See Appendix A. The average duty
cycle can be measured for signals up to 4 kHz.
Max measurement interval: for frequency or duty cycle measurements the
datalogger must request a measurement at an
interval no longer than 15.9375 seconds. Each
channel can be measured at different intervals,
both for frequency and duty cycle.
1 If more detailed input/output characteristics are required, experienced users
should consult the equivalent circuit diagrams shown in Figure 2.
2 See Appendix A for a more detailed discussion of switch debounce, resolution
and accuracy.
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