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

XNX Universal Transmitter
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
configuration� 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 specification
• The physical layer is tested according to HART Physical
Section 2 - Installation and Operation
Layer Test Procedure, HCF_TEST-2�
• Data transfer rate: 1200 bps�
HART devices can operate in point-to-point or multidrop
configurations�
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, configuration 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�
Multiplexer
Note: Instrument power is provided by an interface
Barrier
Field Device
Figure 57. Point-to-Point Mode of Operation
51
Control System
or Other Host Application
or external power source that is not shown.
Handheld Terminal