Setting pushbutton unit illumination, function - GF54.30-P-2010SK
MODELS 171.4
Presentation of duty cycle
The lamps of the switch and controls illumination are actuated with a square-wave voltage U58d
The light units (L) are triggered during the ramp-up period (t1). There is a pause until this period has elapsed.
This process is continuously repeated. The changes are executed so quickly that the eye dos not perceive any flickering in the lights (L).
The ratio of active period (t1) to period duration (T) is the pulse-duty factor. The period duration (T) remains constant, while the active period (t1) is the time within the period during which voltage is being applied.
A higher pulse-duty factor corresponds to a higher mean current consumption and a corresponding increase in the intensity of the illumination (L).
The illustration shows the curve for square-wave signal U58d at the Terminal 58d output terminals for various control units.
A pulse-duty factor of 100 % corresponds to DC power. Power is not supplied when the duty cycle is 0 %.
The rheostat for instrument lighting and search illumination (+/-) in the instrument cluster (A1) can be used to adjust the intensity of the search illumination. The pulse-duty factor regulates closed-loop control.
Signal flow:
- When the parking lights are on (Terminal 58d ON), the SAM control unit with fuse and relay module for the driver's side (N10/1) relays the signal to the Class B Controller Area Network (CAN-B).
- The instrument cluster module (A1) registers the signal and relays a pulse-duty factor to CAN-B via the Class C Controller Area Network bus (CAN-C).
- Various electronic control units pick up this signal and respond by triggering the light units (L) in the search illumination with the square-wave voltage U58d.
Advantages of this type of illumination adjustment:
- The intensity of the illumination from the lights (L) does not vary as a function of the number of light units (L).
- Every control unit connected to CAN-B or CAN-C can regulate illumination from its own light units (L) to the level specified by the instrument cluster module (A1).
The instrument cluster module (A1) responds to "Terminal 58d OFF" (parking lights OFF) by transmitting "pulse-duty factor at Terminal 58d = 0 %".
Depending on the adjustment setting, at "Terminal 58d ON" (parking lights ON) the transmitted pulse-duty factor can vary between 12 % and 100 %.
| Instrument cluster (IC), location/task | GF54.30-P-3039SK |