IB-106-340
7-1
SECTION VII. HART/AMS
7-1.
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
×
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 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
4-20
mA Oxymitter 4000 current loop. The
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 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.
7-2.
HART COMMUNICATOR SIGNAL LINE
CONNECTIONS. The HART Communicator can
connect to the Oxymitter 4000 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.
LOOP CONNECTORS
USE INTERFACE
00275 0013 ONLY
SERIAL PORT & BATTERY
CHARGER MUST
NOT BE USED IN
HAZARDOUS AREAS
SERIAL PORT
AC L1
AC N
+
+
-
-
4-20
TERMINAL BLOCK
LOOP CONNECTORS
4-20 mA SIGNAL LINE
HART
COMMUNICATOR
RL
250
≥
Ω
ANALOG OUTPUT DEVICE
LEAD SET
HART COMMUNICATOR
REAR PANEL
23230001
Figure 7-1. Signal Line Connections, > 250 Ohms Lead Resistance
Содержание Oxymitter 4000
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