Emerson Rosemount 248 Reference Manual page 43

Reference Manual
00809-0100-4825, Rev CB
1.
2.
3.
4.
After completing the test procedure, the display returns to the loop test screen and another
output value can be chosen.
Master reset
Fast Key sequence
Master Reset resets the electronics without actually powering down the unit. It does not return
the transmitter to the original factory configuration.
Active calibrator
Fast Key sequence
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
Fast Key sequence
The Signal Condition command allows viewing or changing of the primary variable lower and
upper range values, sensor percent of range, and sensor damping.
Configuration
Connect a reference meter to the transmitter. To do so, shunt
the transmitter power through the meter at some point in the loop.
From the HOME screen, choose 1 Device Setup, 2 Diag/Serv, 1 Test Device, 1 Loop
Test before performing a loop test.
Choose a discreet milliampere level for the transmitter to output. At the CHOOSE
ANALOG OUTPUT prompt, choose 1 4mA, 2 20mA, or choose 3 other to manually input
a value between 4 and 20 mA.
Check the current meter installed in the test loop to verify that it reads the value that
was commanded to output. If the readings do not match, either the transmitter
requires an output trim or the current meter is malfunctioning.
1, 2, 1, 3
1, 2, 2, 1, 3
1, 4, 2
Section 3: Configuration
March 2014
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