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Reference Manual
00809-0100-4021, Rev DA
November 2004
Rosemount 3144P
3-12
HART
Apply changes made (see “Apply AMS Changes” on page 3-5).
Hot Backup Configuration
The Config Hot BU command configures the transmitter to automatically
use Sensor 2 as the primary sensor if Sensor 1 fails. With Hot Backup
enabled, the primary variable (PV) must either be First Good or Sensor
Average (see “Average Temperature” on page 3-10 for details on using
Hot Backup when PV is Sensor Average). You can map Sensors 1 or 2 as
the secondary variable (SV), tertiary variable (TV), or quaternary variable
(QV). In the event of a primary variable (Sensor 1) failure, the transmitter
enters Hot Backup mode and Sensor 2 becomes the PV. The 4–20 mA
signal is not disrupted and a status is available to the control system (via
HART) that Sensor 1 has failed. An LCD display, if attached, also displays
the failed sensor status.
While configured to Hot Backup, if Sensor 2 fails while Sensor 1 is still
operating properly, the transmitter continues to report the PV 4–20 mA
analog output signal while a status is available to the control system (via
HART) that Sensor 2 has failed. In Hot Backup mode, the transmitter will
not revert back to Sensor 1 to control the 4–20 mA analog output until the
Hot Backup mode is reset. Reset Hot Backup either by re-enabling via
HART or by briefly powering down the transmitter.
To set up and enable the Hot Backup feature for the 3144P transmitter,
perform the following procedure:
1. Attach any two sensors to the transmitter as shown in Figure 2-12 on
page 2-16.
2. From the Home screen, select 1 Device Setup, 3 Configuration, 1
Variable Mapping, 5 Variable Re-map to set primary, secondary, tertiary,
and quaternary variables. The communicator displays the PV, SV, TV,
and QV menus in succession.
3. Set PV as First Good or Sensor Average; set secondary, tertiary, and
quaternary variables as desired.
4. Select OK after verifying the variable settings from the Variable Mapping
menu.
5. Select OK to return the control loop to automatic control. Select HOME
to return to the Home screen.
6. From the Home screen, select 1 Device Setup, 3 Configuration, 2
Sensor Configuration, 1 Change Type and Conn, 3 Sensor 1 Setup to
configure Sensor 1.
7. Set the sensor type, number of wires, damping, and units for Sensor 1.
8. Select SEND to download the new data to the transmitter. Select HOME
to return to the Home screen.
9. Repeat Steps 5, 6, and 7 for Sensor 2 using 4 Sensor 2 Setup.
HART Fast Keys 1, 3, 3, 4