mAindicating

mAindicating is a term used in electronics and process instrumentation to describe the practice of indicating measurements by converting the value of a physical quantity into a current signal, typically in the milliampere (mA) range. The most common embodiment is the 4-20 mA current loop, where a sensor or transmitter in the field generates a current between 4 and 20 mA proportional to the measured quantity, such as temperature, pressure, or level.

In a typical setup, a two-wire loop provides both power and signal. The transmitter modulates current according to the input, while a distant indicator, recorder, PLC, or panel meter converts the loop current into a readable display or control signal. Modern installations may add digital data via protocols such as HART on top of the analog current signal.

Advantages of mAindicating include simple wiring, good immunity to electrical noise, and the ability to power remote indicators over long distances. Limitations include the need for proper loop calibration and potential issues with loop impedance; designers must ensure that supply voltage and sensor ranges are compatible. While alternatives exist, such as voltage-output sensors or wireless indicators, current-loop signaling remains common in process control owing to its robustness and reliability.

See also: current loop, 4-20 mA, process control instrumentation, HART protocol.