Pulse Measurement Tips; Input Filters And Signal Attenuation; Pulse Count Resolution - Campbell CR300 Series Product Manual

Counting the increase at each rising and falling edge of both channels when channel A
l
leads channel B. Counting the decrease at each rising and falling edge of both channels
when channel B leads channel A.
For more information, see

14.5.5 Pulse measurement tips

PulseCount()
The
the programmed scan interval. The resolution of pulse counters is one count. Counters are read
at the beginning of each scan and then cleared. Counters will overflow if accumulated counts
exceed 4,294,967,296 (2
detailed instruction information and program examples:
https://help.campbellsci.com/crbasic/cr300/.
Counts are the preferred
from a tipping-bucket rain gage or the number of times a door opens. Many pulse-output
sensors, such as anemometers and flow meters, are calibrated in terms of frequency (Hz) so are
usually measured using the
Use the LLAC4 module to convert non-TTL-level signals, including low-level ac signals, to TTL
levels for input to C terminals
Understanding the signal to be measured and compatible input terminals and CRBasic
instructions is helpful. See

14.5.5.1 Input filters and signal attenuation

Terminals configured for pulse input have internal filters that reduce electronic noise. The
electronic noise can result in false counts. However, input filters attenuate (reduce) the amplitude
(voltage) of the signal. Attenuation is a function of the frequency of the signal. Higher-frequency
signals are attenuated more. If a signal is attenuated too much, it may not pass the detection
thresholds required by the pulse count circuitry.See
more information. The listed pulse measurement specifications account for attenuation due to
input filtering.

14.5.5.2 Pulse count resolution

Longer scan intervals result in better resolution.
On a 1 second scan, the resolution is 1 pulse per second. The resolution on a 10 second scan
interval is 1 pulse per 10 seconds, which is 0.1 pulses per second. The resolution on a 100
millisecond interval is 10 pulses per second.
Pulse measurement specifications
instruction uses dedicated 32-bit counters to accumulate all counts over
32
), resulting in erroneous measurements. See the CRBasic Editor help for
PulseCount()
PulseCount()
Pulse input terminals and the input types they can measure
(p. 191).
output option when measuring the number of tips
frequency-output option.
Pulse measurement specifications
PulseCount()
(p. 79).
(p. 191) for
resolution is 1 pulse per scan.
14. Measurements 83