Function and purpose
Signal conversion: Its primary job is to take the raw signal from a temperature sensor and convert it into a standardized output that is easy to interpret.
Standardized output: Common outputs include 4–20 mA analog signals, which are robust against electrical noise, or digital signals like HART, PROFIBUS PA, or Foundation Fieldbus.
Long-distance transmission: The conversion to a standardized signal, especially the 4–20 mA output, makes it possible to send temperature data accurately over long cables without signal degradation.
Interfacing with control systems: It acts as an interface between the sensor and other equipment, such as a PLC, DCS, or SCADA system, enabling the temperature data to be used for process control.
Enhanced accuracy: The process includes signal conditioning such as amplification, linearization, and noise filtering to ensure the final output is highly accurate and stable.
Key components and types
Input: Connects to temperature sensors like resistance temperature detectors (RTDs) or thermocouples.
Output: Provides a standardized 4–20 mA or digital signal.
Housing: Available in various styles, including "head" transmitters that mount directly onto the sensor or remote-mount options.
Intelligence: Modern transmitters are intelligent, offering features like high measurement accuracy, the ability to be calibrated for specific ranges, and digital communication protocols.
