In an instrumentation loop, which component processes and sends a signal?

In an instrumentation loop, which component processes and sends a signal?

• A. The sensor processes and sends the signal.
• B. In an instrumentation loop, the transmitter processes and sends a signal, often converting to a standardized current or voltage loop.
• C. The controller only sets the setpoint and does not transmit signals.
• D. The valve functions as the transmitter.

Answer: (B)

In an instrumentation loop, the device that handles the measurement signal is the transmitter. It sits between the sensor and the controller, taking the raw measurement from the sensor and performing signal conditioning—amplification, filtering, linearization, and sometimes temperature compensation. After conditioning, it converts the signal into a standardized electrical form, typically a 4-20 mA current loop or a 0-10 V signal, and sends it down the loop to the controller. This standardized output is what allows accurate transmission over distance and compatibility with control systems. The sensor provides the initial measurement, but it doesn’t usually process and transmit in the way a transmitter does. The controller receives the transmitted signal and uses it to compare against the setpoint, then generates a control output to drive the final control element. The valve is the actuator that changes the process based on that control signal, not the device that carries the measurement.

In an instrumentation loop, the device that handles the measurement signal is the transmitter. It sits between the sensor and the controller, taking the raw measurement from the sensor and performing signal conditioning—amplification, filtering, linearization, and sometimes temperature compensation. After conditioning, it converts the signal into a standardized electrical form, typically a 4-20 mA current loop or a 0-10 V signal, and sends it down the loop to the controller. This standardized output is what allows accurate transmission over distance and compatibility with control systems.

The sensor provides the initial measurement, but it doesn’t usually process and transmit in the way a transmitter does. The controller receives the transmitted signal and uses it to compare against the setpoint, then generates a control output to drive the final control element. The valve is the actuator that changes the process based on that control signal, not the device that carries the measurement.