Campbell CR800 Series, Руководство оператора

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Section 5. Overview
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low signal is simply sensor ground (0 mV). A single-ended measurement
measures the high signal with reference to ground, with the low signal tied to
ground. A differential measurement measures the high signal with reference to
the low signal. Each configuration has a purpose, but the differential
configuration is usually preferred.
A differential configuration may significantly improve the voltage measurement.
Following are conditions that often indicate that a differential measurement
should be used:
• Ground currents cause voltage drop between the sensor and the signal-
ground terminal. Currents >5 mA are usually considered undesirable.
These currents may result from resistive-bridge sensors using voltage
excitation, but these currents only flow when the voltage excitation is
applied. Return currents associated with voltage excitation cannot
influence other single-ended measurements of small voltage unless the
same voltage-excitation terminal is enabled during the unrelated
measurements.
• Measured voltage is less than 200 mV.
FIGURE 18: Analog Sensor Wired to
Single-Ended Channel #1