6 Highway Addressable Remote Transducer (HART)

6.1 Introduction

HART, an acronym for Highway Addressable Remote Transducer, is an open process control network protocol and was introduced in the late 1980s. It is a hybrid communication protocol that uses the Bell 202 Frequency Shift Keying (FSK) technique to superimpose digital communication signal on top of the analog 4-20 mA current loop signal. It is supported by the HART Communication Foundation (HCF). Unlike the other “open” digital communication technologies applied to process instrumentation, HART is compatible with existing systems.

For many years, the process automation and control industry is dominated by 4-20 mA analog signal to carry process variable (PV) and control signals to and ...

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