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What is HART ?

HART stands for 'Highway Addressable Remote Transducer' and is a standard originally developed as a communications protocol for control field devices operating on a 4-20 mA control signal.

The HART protocol uses 1200 baud Frequency Shift Keying (FSK) based on the Bell 202 standard to superimpose digital information on the conventional 4-20 mA analogue signal. Maintained by an independent organisation, the HART Communication Foundation, the HART protocol is an industry standard developed to define the communications protocol between intelligent field devices and a control system.

HART is probably the most widely used digital communication protocol in the process industries, and:
Is supported by all of the major suppliers of process field instruments.
Preserves existing control strategies by allowing 4-20 mA signals to co-exist with digital communication on existing 2-wire loops.

Is compatible with analogue devices.
Provides important information for installation and maintenance, such as Tag-IDs, measured values, range and span data, product information and diagnostics.

Can support cabling savings through use of multidrop networks.

Reduces operating costs via improved management and utilisation of smart instrument networks.

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