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Manual
00809-0500-4880
5
Using HART
5.1
Overview
The Field Communicator is a handheld communications interface device. It
provides a common communications link to all microprocessor-based instruments
that are HART
To interface with the Rosemount OCX8800, the Field Communicator requires a
termination point along the O
resistance of 250 ohms between the communicator and the power supply. The
Field 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 4-20 mA oxygen output signal. The communicator does not
disturb the 4-20 mA signal, since no net energy is added to the loop. HART
information is not available on the COe output signal.
If you install special software, you may interface the Field Communicator with a
personal computer (PC). You must have an interface adapter to connect the Field
Communicator to a PC. Refer to the proper Field Communicator documentation in
regard to the PC interface option.
5.2
Field Communicator signal connections
The Field Communicator can connect to the Rosemount OCX8800 oxygen analog
output signal line at any wiring termination in the O
There are two methods of connecting the Field Communicator to the signal line.
For applications in which the signal line has a load resistance of 250 ohms or
more, refer to
the signal line load is less than 250 ohms, refer to
250
ohms.
Rosemount OCX8800A
communications
®
compatible.
®
4-20 mA current loop and a minimum load
2
Method 1: For load resistance ≥ 250
Using HART
communications
®
December 2022
4-20 mA current loop.
2
ohms. For applications in which
Method 2: For load resistance <
81
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