RFMOST Bus Frame Analysis & MOST Packet Data Logger Tool
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Introduction : The MOST (Media Oriented Systems Transport) bus protocol is used primarily in automotive infotainment and multimedia systems. It enables audio, video and control data to be transported across vehicle networks with defined frame structures and cycle based scheduling.
MOST Frame Structure
MOST protocol frame differs in the three versions, with their specific field sizes, layout and purposes. FOllowing are generic fields used in different versions of MOST protocol.
- Streaming data channel : This part of the frame carries synchronous data (e.g., audio, video). It is allocated a portion of the frame whose size depends on the boundary descriptor.
- Packet data channel : This carries asynchronous “packet” data like control commands, navigation data, configuration, or higher layer protocol data. Again, its size in a frame depends on the boundary descriptor.
- Control message channel : This is used for control communication among nodes (e.g., network management, node administration, function block commands). In MOST25, control data is spread over multiple frames; for MOST50 and MOST150, it’s in the header.
MOST25 Frame Structure
Frame Size: 512 bits = 64 bytes
MOST50 Frame Structure
Frame Size: 1024 bits = 128 bytes.
MOST150 Frame Structure
Frame Size: 3072 bits = 384 bytes.
MOST Protocol Data logger tool
| Manufacturers | Product/features |
|---|---|
| Vector Informatik | Products: CANoe .MOST and CANalyzer .MOST : Both tools provide detailed analysis of data traffic on the MOST bus, with support for all speed grades (MOST25, MOST50, MOST150) |
| Ruetz System Solutions (an in-tech Company) | TTsuite MOST : The tool is designed for automated compliance testing of MOST devices against the official specifications of the MOST Cooperation. TTsuite offers a scalable framework for testing MOST25, MOST50, and MOST150 systems on both optical and electrical physical layers. |
| K2L, now part of Microchip | OptoLyzer Studio (Software) and OptoLyzer MOCCA series (Hardware Interface). The platform is not limited to MOST; it supports simultaneous analysis of all major automotive bus systems like CAN, LIN, FlexRay, and Ethernet, providing a holistic view of the vehicle network. |
| Microchip Technology | MOST NetServices : This is a library of software components that provides a standardized Application Programming Interface (API) to access all data transport mechanisms of the MOST network |
| SPX/Bosch (Kent-Moore) | EL-51578 M.O.S.T. 50 Test Kit (also known as GM-51578) : The kit is primarily used to diagnose errors on the MOST bus by systematically bypassing individual modules in the ring topology |
Summary: A MOST packet data logger tool facilitates detailed analysis of control, synchronous and asynchronous channels within the MOST network. It helps in validation and troubleshooting of high bandwidth multimedia communication in vehicles.
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