Rosemount Model 3144 and 3244MV Smart Temperature Transmitters
2-18
Special Considerations
To initiate operation between a Model 3244MV transmitter and the
HART Tri-Loop, you must consider the configuration of both the
differential temperature and the Hot Backup features, if used.
Differential Temperature Measurement
To enable the differential temperature measurement feature of a
Model 3244MV transmitter operating in conjunction with the HART
Tri-Loop, adjust the range end points of the corresponding channel
on the HART Tri-Loop to include zero. For example, if you wish the
secondary variable of the transmitter to report differential
temperature, configure the transmitter accordingly (see “Set Process
Variable Output Order” on page 2-17), and adjust the corresponding
channel of the HART Tri-Loop so one range end point is negative
and the other is positive.
Hot Backup
To enable the Hot Backup feature of a Model 3244MV transmitter
operating in conjunction with the HART Tri-Loop, ensure that the
output units of the sensors are the same as the units of the HART
Tri-Loop. You may use any combination of RTDs or thermocouples
as long as the units of both match the units of the HART Tri-Loop.
For more information on configuring the transmitter for Hot
Backup, see page 3-10. See ”Using the Tri-Loop to Detect Sensor
Failures and Sensor Drift” for information on how to use the
Tri-Loop to detect sensor failure and sensor drift.
Using the Tri-Loop to Detect
Sensor Failures and Sensor Drift
The Model 3244MV transmitter outputs a digital HART signal
whenever a sensor failure occurs. If an analog warning is required, the
HART Tri-Loop can be configured to produce an analog signal that can
be interpreted by the control system as a sensor failure.
To set up the HART Tri-Loop to transmit sensor failure alerts, follow
the steps below.
1. Configure the Model 3244MV transmitter variable map as shown
in the table.
2. Configure Channel 1 of the HART Tri-Loop as TV (differential
temperature). If either sensor should fail, the differential
temperature output will be +9999 or –9999 (high or low
saturation), depending on the position of the Failure Mode
Jumper (see “Failure Mode and Security Jumpers” on page 2-7).
3. Select temperature units for Channel 1 that match the
differential temperature units of the transmitter.
Variable
Mapping
PV
Sensor 1 or Sensor Average
SV
Sensor 2
TV
Differential Temperature
QV
As Desired
