Interface Standard

S ensors and actuators are ubiquitous. They are used in a variety of applications that touch people’s lives every day, ranging from industrial automation to environmental condition monitoring and control to intel-ligent transportation systems to homeland defense. So what is a transducer? A transducer is a device that converts energy from one form into another. The transducer may either be a sensor or an actuator. A sensor is a transducer that generates an electrical signal proportional to a physical, biological, or chemical parameter. An actuator is a transducer that ac-cepts an electrical signal and takes a physical action. A smart transducer is the integration of an analog or digital sensor or actua-tor element, a processing unit, and a communica-tion interface [1]. A smart transducer comprises a hardware or software de-vice consisting of a small, compact unit containing a sensor or actuator element, a microcontroller, a com-munication controller and the associated software from signal conditioning, calibration, diagnostics, and communication [2]. Based on this premise, a smart transducer model is shown in Figure 1(a). It consists of four parts: transducers (sensors and actuators), sig-nal conditioning and data conversion, application processor, and network communication. The analog output of a sensor is conditioned and scaled (amplified), then converted to a digital format by an A/D converter. The digitized sensor signal can then be easily processed by a microprocessor using a digital application control algorithm. The measured or calculated parameters can be passed on to a host or monitoring system in a network by means of network communication protocols. In a reverse manner, an actuation command sent from a host via the network can be used to control an actuator