Section 8. Operation
409
P Terminals
•
Maximum input frequency = 250 kHz
•
CRBasic instructions: PulseCount()
High-frequency pulse inputs are routed to an inverting CMOS input buffer with
input hysteresis. The CMOS input buffer is at output 0 level with inputs
≥
2.2 V
and at output 1 level with inputs
≤
0.9 V. An internal 100 k
Ω
resistor is
automatically connected to the terminal to pull it up to 5 Vdc. This pull-up resistor
accommodates open-collector (open-drain) output devices.
C Terminals
•
Maximum
input frequency = <1 kHz
•
CRBasic instructions: PulseCount(), TimerIO()
8.1.3.3.1 Frequency Resolution
Resolution of a frequency measurement made with the PulseCount() instruction
is calculated as
where
FR = r
esolution of the frequency measurement (Hz)
S = scan interval of CRBasic program
Resolution of a frequency measurement made with theTimerIO() instruction is
where
FR = frequency resolution of the measurement (Hz)
R = timing resolution of the
TimerIO()
measurement = 136 ns
P = period of input signal (seconds). For example, P = 1 / 1000 Hz = 0.001
s
E = Number of rising edges per scan or 1, whichever is greater.
Example: E for a 10 Hz input signal
Scan
Rising Edge / Scan
E
5.0
50
50
0.5
5
5
0.05
0.5
1
Summary of Contents for CR3000 Micrologger
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Page 485: ...Section 8 Operation 485 8 11 2 Data Display FIGURE 110 Keyboard and Display Displaying Data ...
Page 487: ...Section 8 Operation 487 FIGURE 112 CR1000KD Real Time Custom ...
Page 491: ...Section 8 Operation 491 FIGURE 116 Keyboard and Display File Edit ...
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Page 564: ...Section 11 Glossary 564 FIGURE 126 Relationships of Accuracy Precision and Resolution ...
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