Section 5. System Overview
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 the 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
Figure 19. Analog Sensor Wired to Differential Channel #1
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