Carmakers have known for years that if they could agree on at least some vehicle standards they could offer better business cases to their suppliers, which would lead to greater competition and lower prices. Global standards for vehicle networks that provide data links between systems and components would invigorate the automotive electronics industry the way PC and Windows standards invigo" />

Issue: Dec 2002


Hansen



Carmakers Get the Hang of Standards

by Paul Hansen

Carmakers have known for years that if they could agree on at least some vehicle standards they could offer better business cases to their suppliers, which would lead to greater competition and lower prices. Global standards for vehicle networks that provide data links between systems and components would invigorate the automotive electronics industry the way PC and Windows standards invigorated the personal computer industry.

Today, some fifteen years after the creation of CAN (controller area network), the first standard network protocol applied widely to automotive platforms, the industry appears to have reached agreement on other standard networks. It is becoming clear that regardless of carmaker, new vehicles will be made using LIN for the lowest data-rate functions, CAN for medium speed, MOST for the high-speed data rates and FlexRay, for safety-critical applications such as steer- and brake-by-wire.

The road to network standards was long and winding, with a couple of detours and dead ends along the way. Take CAN for instance. In 1994, the Big Three carmakers tried to agree on a standard mid-speed networking specification called SAE J1850, but the standard was written to accommodate two quite different protocols, one for Ford and another for GM and Chrysler. The Big Three would have saved a lot of effort had they instead chosen to adopt the CAN network. The CAN protocol is now widely adopted globally and J1850 will no longer be sourced on new platforms.
 
Six years was wasted on another standard. AMI-Cs IDB Automotive Multimedia Interface Collaborations ITS Data Bus standard was designed so suppliers could plug in aftermarket electronics through a standard connector that could access some vehicle data and functions without corrupting the vehicles control systems or wiring. Even with the support of the SAE, IDB was never adopted by carmakers because of a lack of interest and because its networks data rate wasnt fast enough to handle even audio.
 
A faster more promising standard that could handle not only audio but also video is already gaining acceptance by the German carmakers and now looks like the one that most of the worlds carmakers are likely to adopt. MOST, for Media Oriented Systems Transport, is a plastic fiber-optic digital multimedia network. Applications include multi-peripheral sound systems and video entertainment systems. Collaborative work on MOST began in 1997 by a small group of founders: including Mercedes and BMW. To date, 60 companies have taken membership in MOST including 13 other carmakers. MOST has been in production since July 2001 on the BMW 7-series, since March 2002 on the Mercedes E-class and since June 2002 on the Audi A8. It took just five years to bring MOST from concept to production.
 
Along with MOST, considerable progress has been made by the LIN (Local Interconnect Network) consortium. A low-speed network protocol, LIN will be used in doors, roofs, the steering wheel and seats to connect switches and relays to actuators. LIN has already been employed in the 2001 Mercedes SL. LIN links are also slated for calendar-year 2002 introduction in the E-class. Over the next several years, all Mercedes platforms will get LIN networks. LIN Steering Committee members include BMW and DaimlerChrysler.
 
In order to implement brake-by-wire, slated for production in some luxury vehicles perhaps as early as 2006 or 2007, and steer-by-wire systems, safety-critical data communications are essential. Two contenders for a safety-critical network emerged in Europe: Time-Triggered Protocol (TTP) and FlexRay. The FlexRay consortium was founded by BMW, Mercedes, Motorola and Philips in the fall of 2000, and is gaining widespread acceptance today. Recently, Volkswagen AG informally agreed that it too would join Mercedes, GM, Ford, BMW and others to develop and promote FlexRay.






 LIN, FlexRay and MOST: 

Besides being pioneered by Mercedes and BMW, these successful projects LIN, FlexRay and MOST share some common methods, which should serve as a model for creating the next international standards. Founding carmakers were ready to put the standard protocols quickly into production. Protocol development groups were kept small, including just a few carmakers and a couple key suppliers. Once production specs were fixed, they sought a wider membership. Goals and scope of the standards were limited so they could be easily accomplished.


 Paul Hansen is a strategy consultant in Portsmouth, New Hampshire. He publishes The Hansen Report on Automotive Electronics, a business and technology newsletter. http://www.hansenreport.com/



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