Clear Cal Const:
This will clear the constants loaded into the PC (not the probe).
Any changes made
to the constants not sent to the probe will be lost.
Reload Cal Constants:
This will re download the calibration constants from the probe.
Any changes
made to the constants not sent to the probe will be lost.
Stop Probe:
This will stop the probe from outputting raw sensor values.
Start Probe:
This will start the probe from outputting raw sensor values.
Upload Cal Const:
If calibration constants are located in a file they can be uploaded into calibration
table on PC and into the probe. Calibration constants in the PC and the probe will be overwritten.
Save Cal Const:
This will save the calibration constants in the calibration constants table in the PC
to a “.cal” file.
Calibration Overview
To calibrate, choose the parameter on the left and then the Calibrate Low Point or Calibrate High
Point buttons. The raw sensor value will populate to the Raw Sensor Value text box and the
temperature will also populate if it is required for the calibration (ie automatic temperature
compensation).
Press Hold when the raw value stabilizes. Note that as the raw values are very sensitive at 18bit
resolution the last 1 or 2 digits may not stabilize. This is okay and is likely background noise.
While calibrating the sensors, the constants will be changed in the PC.When SEND CALIBRATION TO
PROBE button is pressed, the constants sent and loaded into the probe. Bearing in mind that the
constants are not loaded till sent, but it is possible to check the calibrated values which are
simulated at the bottom of the screen under Simulated probe values.
IMPORTANT NOTE: The calibration is not loaded in the probe till the SEND CALIBRATION TO
PROBE button is pressed and the probe accepts the new constants!
Temperature Calibration
The temperature calibration should vary very little over the lifetime of the instrument however it is
worth checking on the accuracy of your temperature measurements before calibrating the
dissolved oxygen, conductivity or salinity sensors as they are very sensitive to temperature.
Temperature calibration is performed at two temperatures. The low temperature must be between
0 and 20
o
C and the high temperature must be between 30 and 50
o
C. A thermometer to at least
0.1
o
C accuracy and resolution must be used. To calibrate temperature, proceed as follows:
Select TEMPERATURE button from the list of parameters. The press Low or High button to start the
raw sensor values populating to the screen. Immerse the probe in a stirred water bath held at a
constant temperature– note thermal inertia will occur to the sensor so a period of waiting for the
probe to reach a constant temperature is required. Make a note of the temperature on the
calibration thermometer and press HOLD. Enter the set point value and press CALIBRATE AND SAVE
BUTTON. The temperature calibration is now complete for that set point.
NOTE: If a thermometer accuracy is less than 0.1
o
C it is best to only check the temperature and not
calibrate as the accuracy is not high enough.