
7
HART
®
/AMS
WARNING
The HART option is not protected by energy limiting barriers.
Do not interface with the HART option from within the hazardous area.
Route the 4-20 mA cables and make the connections outside the hazardous area.
This is the case even when using the intrinsically safe version of the handheld
communicator.
7.1
Overview
The HART
®
communicator is a handheld communications device. It provides a common
communications link to all microprocessor-based instruments that are HART compatible.
The handheld communicator contains an 8 x 21 character liquid crystal display (LCD) and
25 keys. A pocket-sized manual, included with the HART Communicator, details the
specific functions of each key.
To interface with the transmitter, the HART Communicator requires a termination point
along the 4-20 mA current loop and a minimum load resistance of 250 ohms between the
communicator and the power supply.
The HART Communicator accomplishes its task using a frequency shift keying (FSK)
technique. With FSK, high-frequency digital signals are superimposed on the transmitter's
4-20 mA current loop. The HART Communicator does not disturb the 4-20 mA signal,
since no net energy is added to the loop.
You can interface to the HART Communicator with a personal computer (PC) after
installing the special software. To connect the HART Communicator to a PC, you need an
interface adapter. Refer to the proper HART Communicator documentation to learn more
about the PC interface option.
7.2
HART
®
Communicator signal line connections
The HART Communicator can connect to the transmitter's analog output signal line at any
wiring termination in the 4-20 mA current loop.
There are two methods of connecting the HART Communicator to the signal line. For
applications in which the signal line has a load resistance of 250 ohms or more, refer to
Method 1. For applications in which the signal line load resistance is less than 250 ohms,
refer to Method 2.
Reference Manual
HART
®
/AMS
00809-0100-4340
October 2019
Rosemount Oxymitter 4000
103
Summary of Contents for Rosemount Oxymitter 4000
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