Final answer:
Resistance in wires and connections and temperature variations in resistance are measurement concerns in a distributed control system employing single loop controllers.
Step-by-step explanation:
Resistance in wires and connections and temperature variations in resistance are two measurement concerns in a distributed control system employing single loop controllers that use the charge balance method of analog/digital conversions. The resistance in the wires and connections cannot be made zero and may change over time, affecting the accuracy of measurements. Temperature variations in resistance can be reduced but not completely eliminated, limiting the precision of the measurements. However, digital devices that are more sensitive to smaller currents than analog devices can improve the accuracy of null measurements by allowing the current to be closer to zero.