Emerson Rosemount 644 Reference Manual page 31

Reference Manual
00809-0200-4728
Figure 2-12: Configuring Hot Backup with LOI
VIEW CONFIG
SENSOR CONFIG
UNITS
RERANGE
LOOP TEST
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* Available only if option code (S) or (D) is ordered.
** Available only if option codes (S) and (DC) are both ordered, or if option codes (D) and
(DC) are both ordered.
For information on using Hot Backup with HART Tri-Loop
the HART
2.7.4 Sensor drift alert configuration
The sensor drift alert command allows the transmitter to set a warning flag (through
HART), or go into analog alarm when the temperature difference between Sensor 1 and
Sensor 2 exceeds a user-defined limit.
This feature is useful when measuring the same process temperature with two sensors,
ideally when using a dual-element sensor. When sensor drift alert mode is enabled, the
user sets the maximum allowable difference, in engineering units, between sensor 1 and
sensor 2. If this maximum difference is exceeded, a sensor drift alert warning flag will be
set.
Though it defaults to WARNING, when configuring the transmitter for sensor drift alert,
the user also has the option of specifying the analog output of the transmitter go into
ALARM when sensor drifting is detected.
Note
Using dual sensor configuration in the Rosemount 644 Transmitter, the transmitter
supports the configuration and simultaneous use of Hot Backup and sensor drift alert. If
one sensor fails, the transmitter switches output to use the remaining good sensor. Should
the difference between the two sensor readings exceed the configured threshold, the AO
will go to alarm indicating the sensor drift condition. The combination of sensor drift alert
and Hot Backup improves sensor diagnostic coverage while maintaining a high level of
availability. Refer to the Rosemount 644 FMEDA report for the impact on safety.
Emerson.com/Rosemount
Tri-Loop.
CALIBRAT
DAMPING
VARIABLE MAP
TAG
ALM SAT VALUES
PASSWORD
SIMULATE
HART REV
HOT BACK CONFIG**
DRIFT ALERT**
....
™
see
Configuration
March 2021
HOT BACK MODE
HOT BACK PV
HOT BACK RESET
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EXIT MENU
Using the transmitter with
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