Fiber Optic Use

Fiber optic use in the E65/E66

Two optical bus systems have been developed for the E65/E66:

- MOST bus
- byteflight

The light wavelength is 650 nm (red light).

In order that the fiber-optic cables for the various bus systems can be distinguished, four different colors are currently used:

- Yellow byteflight
- Green MOST
- Orange service replacement line for byteflight (byteflight is not repairable).
- Black service repair line for MOST.

MOST Bus







The MOST bus transmits all data required by the communication and information systems in the vehicle. MOST stands for Media Orientated Systems Transport.

The connection between the individual control units is provided by a ring bus which transports the data in one direction only. That means that a control unit always has two optical fiber cables - one for the transmitter and one for the receiver.

The MOST control units are linked exclusively by fiber-optic connections. Therefore, the transmitter and receiver diodes can be positioned anywhere within the control unit as optical fibers are used inside the control unit as well.







As a result of the receiver modules being set far into the control unit, the fiber ends can be set back inside the wiring loom connector.

This provides additional protection for the delicate fiber ends.

The 2-pin fibre-optic module is identical on all types of connectors.




Component families and connectors are defined as standards within the MOSTB consortium.

Pin 1 is always assigned to the incoming optical fiber and Pin 2 to the outgoing optical fiber.

byteflight







In contrast with the MOST bus, the byteflight is a star bus which transports data in two directions. That means that there is only one fiber-optic cable for each control unit.

The transmitter is immediately above the receiver. Both are integrated in the control unit's connector strip.

Due to those differences from the MOST bus, a different connector system is required.

Since the byteflight is connected directly to the diode, the protruding fiber end has to be protected by a flap.

This is automatically opened as the connectors are joined up.