Hart/Ams; Overview - Emerson Rosemount Oxymitter 4000 Reference Manual

July 2018

HART/AMS

The HART option is not protected by energy limiting barriers. It must not be interfaced
from within the hazardous area. The 4-20 mA cables should be routed and the
connections made outside the hazardous area. Note that this is the case even when using
the intrinsically safe version of the handheld communicator.

Overview

The HART Communicator is a handheld communications interface 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 all the keys.
To interface with the Hazardous Area Oxymitter 4000, 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 the use of FSK, high-frequency digital communication signals are
superimposed on the Hazardous Area Oxymitter 4000'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.
The HART Communicator may be interfaced with a personal computer (PC), providing
that special software has been installed. To connect the HART Communicator to a PC, an
interface adapter is required. Refer to the proper HART Communicator documentation in
regard to the PC interface option.
HART/AMS
WARNING
Rosemount Oxymitter 4000
83