Smart transmitters and associated protocols—intelligent hardware

Smart Transmitters and Associated Protocols—Intelligent Hardware 

An instrument which not only measures a variable, but also carries out further processing in order to refine the data obtained before presentation either to an observer or to some other stage of the system, is generally termed intelligent or smart. In practice, additional functions are usually available as well as the data-processing facility and these are all normally contained within the transmitter of the measuring device. These so-called smart transmitters are microprocessor-based and enable the device  

The cost of an intelligent instrument can be twice that of the equivalent device without the smart facility (the latter is termed a dumb instrument)(99). However, the use of a smart transmitter does generally improve the inherent accuracy of the sensor itself. 

A common feature of smart devices is the ability, either to transmit the normal 4-20 mA analogue output (which is digitally linearised and compensated where necessary), or to provide digital communication with other devices as desired. Digital communication with a smart transmitter can be implemented from a microprocessor within the control room, or by the use of a hand-held terminal. The latter can be inserted at any point within the 4-20 mA current loop and instructions to change the range, calibration, etc. can be sent to a specific smart device(l00 . 

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Smart Transmitters and Associated Protocols—Intelligent Hardware... 

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