Displaying time, function - GF54.30-P-3024R

MODEL 230

Block diagram

Fig 1: Displaying Time - Block Diagram

Courtesy of MERCEDES-BENZ USA

The components labeled with dotted lines are only applicable to vehicles equipped with Comand (code 352a).

Function requirements

Terminal 15 ON

General

Time measurement (clock) requires a periodic process with a cycle duration of high accuracy (e.g. earth rotation, pendulum oscillation). Likewise, an electronic clock requires an electric clock signal with high frequency accuracy. This clock signal is usually derived from the extremely constant mechanical oscillations of an oscillator crystal . A quartz (1) with a very high frequency (several MHz) is normally used. This frequency is then scaled down to the required frequency of 1 Hz using an electronic frequency scaler (2). In this way, the display (3) receives one electrical pulse every second to change the display.

Displaying the time in vehicles without COMAND

The electronic clock (A70) works according to the principle described above. Electronics are also required to set the clock. The clock is adjusted via the "Settings" menu using the buttons on the multifunction steering wheel:

Scroll forward/back pushbutton (S110s1)
System select pushbutton (S110s3)
Pushbutton + and a, setting of specific functions and volume control (S111s1)

The signals from these pushbuttons are registered by the steering column module (N80) and relayed to the instrument cluster (A1) over the interior compartment CAN. (For further information see Operating Instructions)

The liquid crystal display (LCD) for the electronic clock (A70) is located in the front PTS warning display in the center of the instrument panel (A44/4). This is connected to the instrument cluster (A1) via a serial interface (LIN bus; LIN= Local Interconnect N etwork).

The instrument cluster (A1) also relays the current time as a message onto the interior compartment CAN.

Displaying the time in vehicles with COMAND (code 352a)

In vehicles with COMAND, the instrument cluster (A1) adopts the time from the COMAND operating, display and control module (A40/3). The time is therefore set there.

The time information is relayed onto the interior compartment CAN every minute as a message by the COMAND operating, display and control module (A40/3).

If the equipment code for COMAND is set in the instrument cluster (A1) (code 352a), it uses this time information.

If GPS signals are received from the GPS antenna (A2/23), these signals can be used to switch automatically between summer and winter time (daylight saving time) . Adjustments for different time zones are also automatic. This is made possible by the GPS geolocational data monitored by COMAND.

If it fails to receive time information from COMAND, the instrument cluster accesses its own internal clock (timer). The internal clock is not manually adjustable.

Instrument cluster, operating instructions		GF54.30-P-0002-05R
Cockpit Management and Data System (COMAND), function	MODEL 230 with CODE (352a) COMAND operating and display system except CODE (491) US version except CODE (498) Japan version.	GF82.85-P-0003RA
Instrument cluster (IC), location / task		GF54.30-P-3039R