A field device such as a transmitter in a process control system includes conversion circuitry coupled between Fieldbus interface circuitry and transmitter interface circuitry. The transmitter includes a transducer for sensing a process variable and providing a transducer output. Measurement circuitry couples to the transducer output, processes the transducer output and provides a measurement output. The transmitter interface circuitry couples to the measurement circuitry and provides an interface output representative of the measurement output. Further, the transmitter interface circuitry receives a transmitter command and responds in accordance with the transmitter command. The Fieldbus interface circuitry is adapted to couple to a process control loop which operates in accordance with the Fieldbus standard.