Emerson Rosemount 248 Reference Manual page 39

Reference Manual
00809-0100-4825
Active calibrator
The Active Calibrator Mode command enables or disables the pulsating current feature.
The transmitter ordinarily operates with pulsating current so that sensor diagnostic
functions, such as open sensor detection and EMF compensation, can be performed
correctly. Some calibration equipment requires steady current to function properly. By
enabling the Active Calibrator Mode the transmitter stops sending pulsating current to the
sensor and supplies a steady current. Disabling the Active Calibrator returns the
transmitter to the normal operating state where it sends a pulsating current to the sensor,
enabling the sensor diagnostic functions.
The Active Calibrator Mode is volatile and is automatically disabled when power is cycled,
or when a Master Reset is performed using the Field Communicator.
Note
The Active Calibrator Mode must be disabled before returning the transmitter to the
process to ensure that the full diagnostic capabilities of the Rosemount 248 are available.
Disabling or enabling the Active Calibrator Mode will not change any of the sensor trim
values stored in the transmitter.
Sensor review
The Signal Condition command allows viewing or changing of the primary variable lower
and upper range values, sensor percent of range, and sensor damping.
Write protect
The Write Protect command protects the transmitter configuration data from accidental
or unwarranted changes. To enable the write protect feature:
Procedure
1. From the HOME screen select 1 Device Setup, 2 Diag/Service, 3 Write Protect.
2. Choose Enable WP.
HART output
The HART Output command allows the user to make changes to the multidrop address,
initiate burst mode, or make changes to the burst options.
Alarm and saturation
The Alarm/Saturation command allows the alarm settings (Hi or Low) and saturation
values to be viewed and changed. To change the alarm values and saturation values, select
the value to be changed, either 2 Low Alarm, 3 High Alarm, 4 Low Sat., or 5 High Sat then
enter the desired new value, which must fall within the guidelines:
• The low alarm value must be between 3.50 and 3.75 mA
• The high alarm value must be between 21.0 and 23.0 mA
Rosemount 248 Temperature Transmitter Reference Manual
Note
To disable write protect on the Rosemount 248, repeat the procedure, replacing
Enable WP with Disable WP.
Configuration
May 2019
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