What is a Current Loop?

A current loop is a basic DC circuit, consisting of a transmitter, one or more receivers, and a power supply.

The transmitter is the sensor measuring the quantity we are interested in.

The receiver is the Samsara Input Module, or other device in place to monitor the sensor.

The power supply is required to energize the circuit.

The sensor/transmitter varies the current flowing around the circuit in response to the value being monitored by the sensor.  Normally the range of variation of the current flow is between 4 and 20 milliamps (mA).  The transmitter will output 4mA to indicate its minimum sensor value, and 20mA to indicate its maximum sensor value.