Basic Device Definitions: Sensor, Transducer, Transmitter, Actuator

Basic Device Definitions

In industrial automation, devices are categorized based on their functional role in the control loop.

1. Sensor

The first element in the measurement chain. It detects a physical parameter (pressure, temperature, flow, force) and converts it into a measurable electrical signal.

• Example: A strain gauge on a load cell or a thermocouple bead.

2. Transducer

A broader term for a device that converts energy from one form to another. While often used interchangeably with "sensor", it technically refers to the element doing the physical-to-electrical conversion. It often produces a weak, raw signal (mV).

3. Transmitter

A device that takes the weak signal from a sensor/transducer, processes it, and converts it into a standard industrial signal (like 4-20mA, 0-10V, or Modbus) that can be transmitted over long distances to a PLC or SCADA system without degradation.

• Our Solution: The GDT Digital Transmitter is a prime example, converting loadcell mV signals into stable digital outputs.

4. Actuator (Final Control Element)

The device that sits at the end of the control loop. It receives a signal from the controller (PLC) and converts it into physical mechanical action to change the process.

• Examples: Electric motors, pneumatic valves, hydraulic pistons.