Emerson OXYMITTER 4000 - Manual (Page 97)

Instruction Manual
IB-106-340 Rev. 3.0
December 2003
Rosemount Analytical Inc. A Division of Emerson Process Management HART/AMS 7-1
Oxymitter 4000
SECTION 7
HART/AMS
7-1 OVERVIEW
The HART Communicator is a handheld com-
munications interface device. It provides a
common communications link to all microproc-
essor-based instruments that are HART com-
patible. 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 spe-
cific 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 com-
municator 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 communica-
tion 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 spe-
cial 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 applica-
tions in which the signal line has a load resis-
tance 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.
a. Method 1, For Load Resistance
≥≥≥≥ 250 Ohms
Refer to Figure 7-1 and the following steps
to connect the HART Communicator to a
signal line 250 ohms or more of load
resistance.
Explosions can result in death or seri-
ous injury. Do not make connections
to the HART Communicator's serial
port, 4-20 mV signal line, or NiCad
recharger jack in an explosive
atmosphere.
Using the supplied lead set, connect the
HART Communicator in parallel to the
Oxymitter 4000. Use any wiring termination
points in the analog output 4-20 mA signal
line.
b. Method 2, For Load Resistance
< 250 Ohms
Refer to Figure 7-2 and the following steps
to connect the HART Communicator to a
signal line with less than 250 ohms load
resistance.
Explosions can result in death or seri-
ous injury. Do not make connections
to the HART Communicator's serial
port, 4-20 mA signal line, or NiCad
recharger jack in an explosive
atmosphere.
1. At a convenient point, break the analog
output 4-20 mA signal line and install
the optional 250 ohm load resistor.
2. Plug the load resistor into the loop
connectors (located on the rear panel
of the HART Communicator).