Setting push-button unit illumination, function - GF54.30-P-2010PM
MODELS 203.0 /2 /7 as of 24.4.04
Representation of duty cycle
Duty cycle term. 58d
The lamps (L) of the switch and controls illumination are actuated by a square-wave voltage U 58d .
The lamps (L) are actuated in the make-time (t1), then a pause follows up to the end of the period. This process repeats itself over and over again. This change happens so quickly that the eye does not notice any flickering of the lamps (L).
The ratio of the make-time (t1) to cycle duration (T) is called the duty cycle. In the process the cycle duration (T) is constant and the make-time (t1) is the time in which voltage is applied within a period.
The larger the duty cycle, the larger the average power consumed and therefore the brightness of the lamps (L).
This illustration shows the curve of square-wave voltage U58d which applies at the outputs circuit 58d of various control units. The upper drawing shows a duty cycle of 80%, the lower a duty cycle of 40%. A duty cycle of 100% corresponds to a direct voltage. Power is not supplied when the duty cycle is 0%.
The brightness of the switch and controls illumination can be adjusted with the variable resistor for instrument illumination (A1r1) of the instrument cluster (A1). The control is effected via the duty cycle of circuit 58d.
Signal flow:
- If the standing lamp "circuit 58d ON" is switched on, the front SAM control unit with fuse and relay module (N10/1) places a message on the Controller Area Network bus class B (interior) (CAN-B).
- The instrument cluster (A1) receives this message and places the duty cycle circuit 58d as a message on the CAN-B and on the Controller Area Network bus class C (engine compartment) (CAN-C).
- Various control units receive this message and control the lamps (L) of the push-button unit illumination with the square-wave voltage U 58d .
Advantages of this type of illumination adjustment:
- The brightness of the lamps (L) depends on the number of lamps (L).
- Each control unit which is connected to CAN-B or CAN-C can actuate its lamps (L) with the brightness specified by the instrument cluster (A1).
With "circuit 58d OFF" (standing lamp OFF) the instrument cluster (A1) transmits the message "duty cycle circuit 58d = 0%".
With "circuit 58d ON" (standing lamp ON) the duty cycle transmitted may vary from 12% to 100% depending on the adjustment.
| Instrument cluster (IC), location/task | GF54.30-P-3039PM |