
Chapter 4 ________________________________________________________________ Operation
VAISALA ______________________________________________________________________ 123
If the adjustment in the AutoCal reaches a preset maximum value or if
the AutoCal correction fails, for example, because of unstable conditions,
a new AutoCal will take place later (if the automatic AutoCal is turned
on).
Automatic AutoCal
As a default, the automatic AutoCal in DMT345 and DMT346 is turned
on. In this mode, the calibration takes place automatically if the dewpoint
or temperature changes significantly, typically more than 10 ºC.
However, if there are no changes in the conditions, the AutoCal will take
place repeatedly after one hour from the last AutoCal.
Manual AutoCal
To ensure that AutoCal has taken place for obtaining the most accurate
measurement in a very dry environment, you can perform Autocal
manually before measuring as follows:
1. Open
the
MAIN MENU
by pressing any of the
▲▼◄►
arrow
buttons.
2. Select
Measuring
, press the
►
arrow button.
3. Select
Manual AutoCal
, press the
►
arrow button.
4. Press
START
to start AutoCal. If the AutoCal conditions are not
fulfilled, a note appears on the display informing that the
calibration cannot be made.
0706-014
Figure 63
Following AutoCal on the Display
5. Press
EXIT
to return to the basic display.
You can also activate Manual AutoCal by pressing both
AUTOCAL
buttons on the transmitter motherboard. These are the same buttons as the
pressure set buttons, but when pressed simultaneously, they will start the
AutoCal procedure. See Figure 57 on page 93 for location of the
AUTOCAL
/pressure set buttons.
If the AutoCal conditions are not fulfilled, a note appears on the display
informing that the calibration cannot be made.