Maintenance - Hach LDO User Manual

Option Description
Hold The sensor output value is held at the current measured value during the calibration procedure.
Transfer A preset value is sent during calibration. Refer to the controller user manual to change the preset
value.
5. The controller will show:
• "Press ENTER when stabilized"
• The current dissolved oxygen measurement
• The current temperature measurement
6. When the measurement is stable, push ENTER. The display will show an entry screen.
Note: The measurement will usually stabilize in 2 to 3 minutes.
If the value does not stabilize, the display will show "Unable to Calibrate" followed by an error
message. Table 4 shows the error message and resolution for calibration problems.
Message Description
Cal fail, offset high The calculated offset value is too high.
Cal fail, offset low The calculated offset value is too low.
Cal fail, unstable The value did not stabilize in the maximum allowed calibration time.
Exit the calibration procedure
1. During calibration, push the BACK key. Three options are shown:
Option Description
ABORT Stop the calibration. A new calibration must start from the beginning.
BACK TO CAL Return to the current calibration.
LEAVE Exit the calibration temporarily. Access to other menus is allowed while the calibration
continues in the background. A calibration for a second sensor (if present) can be started.
To return to the calibration, push the MENU key and select Sensor Setup, [Select Sensor].
2. Select one of the options. Confirm.
Reset calibration defaults
Calibration settings can be reset to the factory defaults. Gain and offset values are set to 1.0 and 0.0,
respectively.
1. Go to MENU>SENSOR SETUP>[Select Sensor]>CALIBRATE>RESET CAL DEFLT.
2. The display will show a confirmation message. Confirm to reset the sensor to the factory default
calibration curve.

Maintenance

Multiple hazards. Only qualified personnel must conduct the tasks described in this section of the
document.
14 English
Table 4 Sample cal error messages
D A N G E R
Resolution
Repeat the calibration.
Repeat the calibration.
Repeat the calibration.