ABSTRACT
A Highway Addressable Remote Transducer (HARTTM) device is a microprocessor-based process transmitter or actuator that supports two-way communications with a host, digitizes the transducer signals, and digitally corrects its process variable (PV) values. This chapter demonstrates the power, the value, and the wide range of HART capabilities and applications. Since 4-20 mA transmitters provide a single PV to the control system via the loop current, early HART development focused on the primary PV. The 4-20 mA current loop communication channel connects the HART field device to the control system. All HART field devices support two communication channels: the traditional current loop and HART communication. HART-communicating devices work well in applications that require intrinsic safety (IS) operation. The simplicity of the HART protocol contributes to its popularity and to the low cost of HART compatible equipment.
