The raw analog output from a thermocouple (TC) or resistance temperature detector (RTD) must be converted into a digital signal before the temperature can be interpreted. It can be sent in its raw form to a simple digital display, small temperature loop controller, transmitter or the temperature I/O card of a larger automation system.

Applications involving heating invariably require temperature measurement instrumentation. Temperature instruments typically consist of a thermowell, a sensor and a transmitter to convert the sensor data to an industry-standard signal such as 4 to 20 mA or fieldbus digital communications.