Honeywell XNX - 2�3 Options; 2�3�1 Local Hart Interface

XNX Universal Transmitter
Section 2 - Installation and Operation
51
2.3 Options
2.3.1 Local HART Interface
Availablewithanysensortechnologyoroption,thisoption
providesanexternalaccesstotheHARTinterfaceinthe
transmitter�AnISbarrierinsidethetransmitterallowstheuserto
attachanexternalhand-heldinterrogatorforprogrammingand
conguration�Theexternalinterfaceisinstalledinthelowerleft
cable/conduitportofthetransmitterandisintrinsicallysafe(IS)�
Figure 56. XNX Universal Transmitter with HART Interface IS Barrier installed
TheHARTprotocolisacommunicationtechnologyusedwith
smartprocessinstrumentation,providingtwo-waydigital
communicationsimultaneouslywiththe4-20mAanalogsignaling
usedbytraditionalinstrumentationequipment�Formore
detailedinformationonHART,seetheHARTProtocolandwww�
hartcomm�org�
ImplementationoftheHARTprotocolintheXNXtransmitter:
• MeetsHART6�0physicallayerspecication
• ThephysicallayeristestedaccordingtoHARTPhysical
LayerTestProcedure,HCF_TEST-2�
• Datatransferrate:1200bps�
HARTdevicescanoperateinpoint-to-pointormultidrop
congurations�
Caution: Deviceaddresschangesmustbeperformedonlyby
qualifiedservicepersonnel.
Point-to-Point Mode
Inpoint-to-pointmode,the4–20mAsignalisusedto
communicateoneprocessvariable,whileadditionalprocess
variables,congurationparameters,andotherdevicedataare
transferreddigitallyviaHARTprotocol(Figure57)�The4–20mA
analogsignalisnotaffectedbytheHARTsignal�
Control System
or Other Host Application
Multiplexer
Barrier
Handheld Terminal
Field Device
Note: Instrument power is provided by an interface
or external power source that is not shown.
Figure 57. Point-to-Point Mode of Operation
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