Chapter 3________________________________________________________ Functional Description
VAISALA ________________________________________________________________________ 23
BLSC Command
The background luminance sensor can be used in a continuous or
day/night switch mode. When you give a positive BLSC value, the
background luminance measurement mode will be continuous. When
you give a zero value, the measurement turns into day/night switch
mode.
When PWL111 is activated, its background luminance value is
reported in message 7 and in the Status message.
Continuous Mode
The following command activates the sensor and gives the positive
scaling factor for the luminance value. See the example below:
>BLSC 1.0
The response is the following:
BL SCALE 1.000
Background luminance is reported in a range of 4 ... 20000 cd/m
2
with
the above settings.
Day/night switch Mode
The following command activates the sensor in day/night switch
mode, that is, the luminance value is either 0 or 1. Zero indicates night
time and one indicates day time. See the example below:
>BLSC 0
Disabling PWL111
The negative scale directs PWD22 to skip the background luminance
action. See the example below:
>BLSC -1
BLCAL Command
PWD22 calculates the new BL scale if the current background
luminance in cd/m
2
is known. The BL scale must be >0. Also the
BLSC sensor must be already activated by the BLSC command. When
you type the following command, PWD22 calculates the BL scale.
>BLCAL 12300
