II - DCE FEL ČVUT v Praze
II - DCE FEL ČVUT v Praze
II - DCE FEL ČVUT v Praze
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4.2 Introduction to HART<br />
Introduction<br />
What is HART?<br />
What advantages<br />
does HART offer?<br />
What are typical<br />
applications of<br />
HART?<br />
I/O Modules with Intrinsically-Safe Signals<br />
C79000-G7076-C152-04<br />
This section provides you with an introduction to HART from a user’s<br />
perspective:<br />
Definition of HART<br />
Advantages of HART analog modules<br />
Typical applications of HART<br />
The HART functions enable you to operate an analog module in conjunction<br />
with digital communication. The HART protocol is generally accepted as a<br />
standard protocol for communication with smart field devices: Hart is a<br />
registered trademark of the “HART Communication Foundation” (HCF),<br />
which retains all rights for the HART protocol. You can find detailed<br />
information about HART in the HART Specification /900/ and in the booklet<br />
/901/ published by Fisher-Rosemount Ltd.<br />
Note<br />
The HART analog modules are designed to be used with version 5.4 of the<br />
HART protocol. Field devices which operate with an earlier version of the<br />
HART protocol are only supported to a limited extent: the command<br />
instruction format must be “long frame,” with one exception: the “short<br />
frame” command format must be used for command 0 (see Table 4-2) to<br />
obtain the “long frame” address. Additional features which are introduced in<br />
Version 6 of the HART protocol have not yet been implemented.<br />
The use of HART analog modules has the following advantages:<br />
Compatibility with analog modules: current loop 4 - 20 mA<br />
Digital communication with the HART protocol<br />
Low power requirements, important for use in hazardous areas<br />
A wide range of field devices with HART functions are now available<br />
Integration of the HART functionality in the S7 system when using HART<br />
analog modules<br />
The following are typical applications of HART:<br />
Installation of field devices (central assignment of parameters)<br />
Modification of field device parameters online<br />
SIMATIC S7 HART Analog Modules<br />
Display of information, maintenance data and diagnostic data for field<br />
devices<br />
Integration of configuration tools for field devices via the HART interface<br />
4-3
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