23
Reference Manual
00809-0200-4728, Rev RA
Section 2: Configuration
April 2015
2.7.3
Hot Backup configuration
The Hot Backup feature 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 Average. See the “NOTE” directly above for details on using Hot Backup when the PV is
set to Average.
Sensors 1 or 2 can be mapped 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 through HART that Sensor 1 has failed. An LCD
display, if attached, displays the failed sensor status.
While configured to Hot Backup, if Sensor 2 fails but 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 through HART that Sensor 2 has failed.
Resetting Hot Backup
In Hot Backup mode, if Sensor 1 does fail and Hot Backup is initiated, the transmitter will not
revert back to Sensor 1 to control the 4–20 mA analog output until the Hot Backup mode is
reset by re-enabling through HART, re-setting it through the LOI or by briefly powering down the
transmitter.
Hot Backup configuration with a Field Communicator
The field communicator will walk you through a method to correctly configure the necessary
elements of the Hot Backup feature.
From the
HOME
screen, enter the Fast Key sequence.
Hot Backup configuration with AMS Device Manager
1.
Right click on the device and select
Configure
.
2.
In the left navigation pane select
Manual Setup
.
3.
On the
Diagnostics Tab
find the
Hot Backup
group box.
4.
Choose the button
Configure Hot Backup
or
Reset Hot Backup
depending on the
desired function and walk through the guided steps.
5.
Select
Apply
when complete.
Hot Backup configuration with LOI
To configure Hot Backup on the LOI, enable the mode and set the PV values. Reference
below for where to find these in the menu.
Device Dashboard Fast Keys
2, 1, 5
Summary of Contents for Rosemount 644
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