MOST25 vs MOST50 vs MOST150: A Comparison of Automotive Bus Types

This page compares MOST25, MOST50, and MOST150, highlighting the key differences between these interface bus types commonly used in the automotive market.

• MOST stands for Media Oriented Systems Transport.
• It’s a high-speed networking technology specifically developed for the automotive industry.
• This technology can be implemented both inside and outside the vehicle, such as in cars.
• It facilitates the transport of audio, voice, data, and video signals over plastic optical fiber.
• The MOST serial bus utilizes a ring topology for connecting devices. Up to approximately 64 devices can be connected on a single ring network.
• Communication over the MOST bus is synchronous.

Let’s delve into the primary differences between MOST25, MOST50, and MOST150 serial bus types.

MOST25 Bus

Here are the key features of the MOST25 Bus:

• Bandwidth: 23 MBaud
• Transmission: Synchronous for streaming data, Asynchronous for other data.
• Physical Layer: Supports both Optical and Copper connections.
• Audio Channels: Supports 15 uncompressed audio channels with CD-quality sound.
• Audio/Video Channels: Accommodates 15 MPEG-1 channels, each using 4 bytes.
• Separate control channel is available.

MOST50 Bus

The MOST50 Bus boasts the following features:

• Bandwidth: Offers double the bandwidth of MOST25.
• Frame Length: Utilizes a frame length of 1024 bits.
• The control channel and two data channels (one for streaming and one for packet data) are identical to those found in the MOST25 bus.
• Supports both optical and electrical physical layers.

MOST150 Bus

The MOST150 Bus presents these notable features:

• Bandwidth: Provides six times the bandwidth compared to MOST25.
• Frame Length: Uses a frame length of 3072 bits.
• Used to implement Ethernet physical layer in the automotive industry.
• Channels: Features an Ethernet channel with adjustable bandwidth, plus 3 channels (e.g., control channel, stream data channel, packet data channel).
• Supports isochronous transfer over a synchronous channel.