The development of intelligent pressure transmitter based on HART Protocol

To solve the problem of the original investment hedge when the fieldbus control system (FCS) substitute the distributed control system (DCS), we design a low-power intelligent pressure transmitter which is compatible with analog signals and digital signals. The pressure transmitter is designed based on HART protocol and composed with MCU module, sensor module, HART communication module, LCD modules and power supply module. The digital signal will be converted into the digital audio signal through the V/I circuit in the design, superimposing on the current loop and realizing the compatible with digital signal and analog signal, at the same time, non-interfering. The total operating current of the entire circuit is no more than 2.1mA, guaranting the low-power requirement. By testing, the intelligent pressure transmitter can be connected with any manual control device or control system which are agreed with HART protocol, and the measurement accuracy has reached the requirement of 0.2%FS.