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68 Configuration, Startup and Operation
S
ection 3: Configuration, Startup and Operation 6888Xi Advanced Electronics Instruction Manual
December 2012 PN 51-6888Xi
was known to contain invalid values. Resetting a calibration will transfer the slope and constant
from calibration 1 in the log into the calibration 0 position. The cell impedance and days since
calibration remain unchanged.
Reset the calibration as follows:
Using the 6888Xi Keypad & Display: IOB 1 Probe 1(or 2)\Calibration\Cal Constants\
Current Cal\Reset Cal
Using the Field Communicator: Configure\Calibration\Calibration Constants\
Reset Calibration Constants
Follow the instructions on the screen to complete the reset function.
3.9 D/A Trim
The D/A trim procedure is used to calibrate the 4-20 mA output signal to a precision mA meas-
urement device. Only the signal to the DCS needs to be trimmed.
D/A Trim with 6888Xi
1. Press the MENU button repeatedly until the IOB1 Probe 1 menu displays.
2. From the main menu, select DIAGNOSTICS then press ENTER.
3. From the DIAGNOSTICS menu, select MAINTENANCE then press ENTER.
4. From the MAINTENANCE menu, select ANALOG OUTPUT then press ENTER.
5. From the ANALOG OUTPUT menu, select TRIM mA OUTPUT then press ENTER.
6. In the first screen, a “Remove Loop from Auto” warning occurs. Remove the 6888Xi from
any automatic controls loops to avoid a potentially dangerous operating condition. Press
ENTER when ready to start.
7. Follow the prompts on the 6888Xi display to perform the trim.
8. Use the RIGHT and LEFT arrow keys to select the digit to edit, then the UP and DOWN arrow
keys to change the value of the digit. Press ENTER to save the new value. Press ENTER to
accept the change.
9. When complete, press EXIT to return to the ANALOG OUTPUT menu.
10. Repeat steps 1 through 9 for PROBE 2 if configured for dual channel.
D/A Trim with 6888Xi and Field Communicator
1. Use the 375/475 Field Communicator to access the main HART menu.
2. From the main menu, select SERVICE TOOLS.
3. From the SERVICE TOOLS menu, select MAINTENANCE.
4. From the MAINTENANCE menu, select ANALOG OUTPUT.
WARNING
Failure to remove the 6888Xi from automatic control loops prior to performing this procedure may
result in a dangerous operating condition.
WARNING
Failure to remove the 6888Xi from automatic control loops prior to performing this procedure may
r
esult in a dangerous operating condition.