scroll through the status list to see the possible cause of the problem. For further description on the error messages see Status Display page 19. Alternatively or select the menu Print Status to print a complete instrument status.
Note:
When battery voltage becomes low a warning (W) is shown in the lower right corner of display. It is still possible to take measurements but when the voltage drops too low, readings can be erroneous.
If in doubt whether the readings are correct make a control measurement on the calibration unit.
Wet night measurement considerations:
Making wet night measurements on warm road surfaces requires special considerations.
Due to the large thermal mass of the road, the road temperature is not influenced very much by the water.
Pouring water on the hot road surface will generate steam. When placing the instrument on the wet road steam will condense in the instrument also on the front window.
Condense on the optical surfaces will result in measure error!
Tests has shown that steam especially condensate on the outside surface of the front window. When removing the instrument from the road, the dew will evaporate quickly and the instru- ment will again take correct readings.
It is recommended to make the "wet measurements" at the lowest possible road temperature!
Print Result: 
Press 
to print the result from last calibration or measurement to the printer.
Menu: 
Press this key to enter the menu section. Press 
again to scroll through the menu structure.
From the Menu it is possible to control most of the instrument settings such as mean calcula- tion, data log functions, real time setup and automatic turn off timer, see Menu system page 21.
The measuring mode (Qd, Rl or both) is set using this key.
The sequence of the menu functions changes depending on what mode the instrument is in at the moment. Example: when taking measurements with the mean calculation on the first func- tion shown will be the Clear Mean function.
Home: 
Press this key to terminate a menu or calibration and display the latest measurement result, if
DELTA | LTL2000S(Q) Retroreflectometer | 4 |