The Hart Smart Straight Trip Actuator Development,

Smart actuator is a necessary part of the process control system, and study of it has not been studied until 1990s in our country, especially for the smart actuator conformed to the fieldbus. From the perspective of fieldbus, HART communication protocol is a kind of transitional product from analog system to digital system. The advantage of HART is that it can maintain the industry standard of analog signal (4~20mA) as well as can transmit data of the process by digital mode. Therefore, the products conformed to HART protocol have the better future in the market.According to HART communication protocol and III actuator model, the study accomplishes the software and hardware design of the smart electric actuator. For hardware, the two circuit boards of control and communication are combined to one, whose functions are completed by one chip of CPU. The power supply and position feedback circuit boards are also simplified to one. In addition, the chip of HT2012 that is recommended by HART foundation carries out the communication. For software, this study completes the codes of instrument control, which include the signal's sampling and filtering, parameter setting, motor controlling and so on. At the same time, the study implements the functions of communication on the basis of the HART protocol, which consist of serial interface interrupt, communication sending and receiving, carrier wave detecting interrupt, etc. The results of test indicate that the functions of software are in accordance with the prescriptions of HART protocol and the functions of hardware achieve the target of design.