Model 275 Universal Hart Communicator; Introduction; Communicator Connections - Siemens 7MF4333 User Manual

UMSITRPDS3-1

2.0 MODEL 275 UNIVERSAL HART COMMUNICATOR

The Model 275 Universal HART Communicator is a handheld interface that provides a common
communication link to SITRANS P transmitters and other HART-compatible instruments.
This section describes HART Communicator connections, liquid crystal display, keypad, and on-line and
off-line menus. It also provides overviews of many Communicator functions. The Communicator is
shown in Figure 2-1. For information about the Communicator's battery pack, Memory Module, Data
Pack, and maintenance procedures, refer to the manual supplied with the Communicator.

2.1 INTRODUCTION

The HART Communicator connects to and communicates with a transmitter or other HART device using
a 4-20 mA loop, provided a minimum load resistance of 250Ω is present between the Communicator and
the power supply. The Communicator uses Bell 202 frequency-shift keying (FSK) to impose high-
frequency digital signals on a standard 4-20 mA current loop. Because no net energy is added to the loop,
HART communication does not disturb the 4-20 mA signal.
The Communicator can be used in hazardous and non-hazardous locations.

2.2 COMMUNICATOR CONNECTIONS

The Communicator can interface with a transmitter from the control room, the instrument site, or any
wiring termination point in the loop. Connections are made through a supplied 40" (1m) cable (dual
banana plug to mini-hook test clips). The connection panel also may have a jack for the optional NiCad
charger, and it has a serial port for a future connection to a personal computer (PC).
To interface with a transmitter or other HART device, connect the HART Communicator in parallel with
the instrument or load resistor. The connections are non-polar. For intrinsically safe FM and CSA wiring
connections, see the manual supplied with the Communicator.
Figure 2-2 illustrates typical wiring connections between the HART Communicator and a loop with a
transmitter or other HART-compatible device in a loop. The Communicator is quickly connected into a
transmitter loop.
November 2010
WARNING
Explosion can cause death or serious injury.
Before connecting the HART Communicator in an
explosive atmosphere, be sure that the instruments in
the loop are installed in accordance with intrinsically
safe or non-incendive field wiring practices.
Refer to the Communicator nameplate and the supplied
manual for certifications and approvals before
connecting, or making a connection to the serial port or
NiCad charger port on the Communicator.
Model 275 Universal Hart Communicator
2-1