Fluke HART 744 - Manual (Page 11)

Documenting Process Calibrator HART Mode
Connecting to a HART Transmitter
3
Connecting to a HART Transmitter
To connect to and begin to communicate with a HART
transmitter, refer to Figure 1 and proceed as follows:
Note
If you only want a communication connection to
a transmitter that is powered in a loop, simply
clip the HART alligator clips to the loop power
terminals on the transmitter, press
r , and you
are done.
1. Connect the calibrator mA jacks to the loop power
terminals of the transmitter.
2. Plug the HART interface cable into the SERIAL
PORT, then connect the alligator clips to the same
terminals as in step 1. There is no right or wrong
polarity.
3. Press the r key.
Note
The square-root symbol on r key is there
only for calculator mode. At all other times, there
is no square-root function associated with the
r key.
4. If the transmitter is not powered by a loop power
supply, press the Loop Power softkey to activate 24V
loop power.
Note
The calibrator provides loop power through an
internal series resistance of 250
Ω
.
If the calibrator shows a measurement of 0 mA,
check for reversed current leads.
If an external loop power supply is used, there
must be a resistance of between 230
Ω
and
270
Ω
connected in series with the external loop
supply and the transmitter.
5. The calibrator tries Poll Address 0 (single transmitter
per loop). If no connection is made, press the Poll
softkey to scan Poll Addresses 1 through 15
(multidrop).
6. Once the calibrator establishes communication with
the transmitter, the Active Device screen appears. In
the case of a multidrop configuration, you must
choose a transmitter from a list, and press
e .