GF54.30-P-2010T Setting Pushbutton Unit Illumination, Function

GF54.30-P-2010T Setting Pushbutton Unit Illumination, Function

Component Identification:

Function requirements:
The switch and controls illumination is activated by the following components:
^ Switching on the vehicle lighting (as long as the standing lamp is active)
^ With the automatic driving lamps via the rain/light sensor (B38/2) and "AUTO" position of the rotary light switch (S1)

When the standing lamp switched on the position of the instrument illumination brightness control and reset button (A1r1) is used as a controlled variable by the overhead control panel control unit (N70), the rain/light sensor (B38/2) is not taken into account. If automatic running lights are set the intensity of the switch and controls illumination is determined by the rain/light sensor (B38/2). Its signals are evaluated by the overhead control panel control unit (N70) and placed on the Controller Area Network bus Class B (interior) (CAN-B).
All the control units which require the signal from the rain/light sensor (B38/2) pick up the signal from CAN-B.

Presentation of duty cycle







Terminal 58d on/off ratio
The lamps of the switch and controls illumination are actuated by means of a square-wave voltage U 58d (see top illustration):
^ The lamps are energized for the period (t 1), followed by a break. After the pause they are energized again, and so on. The change occurs so quickly as to remain imperceptible to the human eye.
^ The ratio of times t1 to T is called the duty cycle. where T is the constant cycle duration and t1 is the time during which power flows during a cycle.
^ The greater the duty cycle (that is to say the power flow duration t 1)), the greater the average power and therefore the brighter the lamps.

The voltage curve U58d is sketched in the illustration as it is applied to the outputs "Circuit 58d" of the various control units. The upper sketch shows a duty cycle of 80 %, the lower a duty cycle of 40 %. A duty cycle of 100 % corresponds to normal direct voltage.

Power is not supplied when the duty cycle is 0 %. Advantages of this type of illumination adjustment:
^ Greater efficiency
^ the intensity of the illumination provided by the lamps remains independent of the number of lamps
^ Each control unit which is connected to the CAN-B o Controller Area Network bus Class C (engine compartment) (CAN-C) and actuates lamps, actuates these lamps with the brightness specified by the instrument cluster (A1)

When the standing lamp is "OFF" the instrument cluster (A1) transmits the message "duty cycle circuit 58d = 0 %". When the standing lamp is "ON" the transmitted duty cycle is adjusted in the range of 12 to 100 % using the instrument illumination brightness control and reset button (A1r1).