Ethernet and Emerging Data Buses in the NAT Vehicle
By Kieran Wright, Molex Incorporated

Ethernet is now fully established as a reliable network that connects our work PCs with various other office devices. However, during the past decade, Ethernet has gradually crossed over into the industrial world, and it can now be found in application areas such as factory automation and process automation.

Modified Ethernet implementations and specifications have evolved to accommodate the more hostile industrial environment. As a result, non-automotive transportation (NAT) application areas requiring Ethernet content, such as marine (LAN for ships), high-speed networking for train carriages, and some mining-related applications, have benefited from industrial Ethernet development and from the general availability of industrial Ethernet switches and interconnects, such as rugged M12 and RJ-45 connectors and cordsets.

As often happens in the NAT industry, well-established technologies and products from the industrial and automotive spaces have crossed over to provide innovative solutions in truck, bus, agriculture, construction, marine, mining, and railway applications. Many Ethernet applications are now emerging alongside CAN-based network protocols (e.g. CANopen), and crossing into NAT space.

For control-type Ethernet applications, the industrial M12 interface format is well accepted. Both M12 and RJ-45 formats are used in NAT applications and are available in sealed IP67 and unsealed versions. M12 connectors and cordsets are particularly suited to the rugged, high-vibration requirements of the vehicle, and are applicable in both internal (cab) and external (outdoor) applications.

For industrial Ethernet and NAT applications, M12 (D-coded) connectors and cables (four-pole, two data pairs) are normally applied. When used in combination with a pass-through M12-to-RJ-45 panel adapter, for instance, a flexible 10Mb/s or 100Mb/s industrial Ethernet application can be facilitated in the vehicle.

More recently, M12 cables and connectors that integrate CAT5e data speed with two separate power circuits (left, Molex's Brad Circular Hybrid Technology (CHT) Connector) have been introduced into the NAT market, allowing devices to be powered up and controlled using the same cable.

To allow vehicle designers to go beyond fast Ethernet speeds into Gigabit Ethernet rates, new M12 Cat6 connectors provide enormous bandwidth (1Gb/s) in a rugged and industrial waterproof M12 format.

Some innovative M12 “push to lock” or “push pull” systems have been developed, and they reduce network installation time, improve the reliability of the connection and, in some cases, provide waterproof sealing to IP69k level. Improving the reliability of the connection (versus screw thread options) increases the protection from vibration and mechanical shock, reducing the potential for loosening, which could lead to intermittent signals, improper sequencing, and ultimately, failure. Achieving IP69k can be attractive particularly for externally placed devices, which can be easily cleaned using a power hose.

For those heavy-duty applications requiring extreme rugged M12 harsh Ethernet interconnects (e.g., for telematic or control applications in off-road vehicles), the Society of Automotive Engineering (SAE) committee defined the J2839 standard. The standard defines the performance requirements, size, and mating interfaces for M12-style four- and five-pole heavy-duty, high-speed datalink connection systems. As an integral participant on the SAE committee, Molex has developed J2839-compliant products rated to 100 lb. (445 Newtons) and 300 lb. (1,335 Newtons) cable pull forces. 

Industrial Ethernet switches (both managed and unmanaged) are widely available for IP67 as well as IP20 or IP30 unsealed cab applications. Typically M12 (D-coded) or RJ-45 cable assemblies are used. High availability is another feature available on industrial Ethernet switches, where an additional, redundant power supply connection is provided. Besides Ethernet switches, manufacturers offer digital network IO modules (typically IP67 rated), which provide Ethernet connectivity for sensors and actuators in measurement and control systems.

Away from the traditional industrial markets, Ethernet has recently attracted the attention of the high-end automobile industry in the form of Ethernet AVB (Audio Video Bridging). This innovation is seen as one of a number of promising network technologies for supporting real-time digital multimedia applications in the vehicle. These same applications are also of interest to non-automotive OEMs in the commercial vehicle (truck), bus, agricultural, and construction equipment sectors.

The key driving applications for vehicle Ethernet AVB are multimedia infotainment and driver assistance. Vehicle manufacturers want to integrate consumer electronic devices, such as MP3 players, mobile phones, and DVD players, into the cab, providing high-quality video displays and monitors, with externally accessible ports, and even the possibility of Internet access.

On the other hand, driver assistance and safety—particularly in commercial vehicles—are escalating the interest in vision systems for applications such as LDW (Lane Departure Warning), collision avoidance, and externally mounted cameras for parking and blind-spot assistance. While connectivity and bandwidth capacity remains a challenge, a high-speed multimedia network is a desirable necessity in the vehicle.

Today’s vehicle-based network systems typically handle data speeds in the upper range of 480Mb/s to 600Mb/s, but some notable systems are in development, including Ethernet AVB (1000BaseT), LVDS (above 1GHz) and 1394Auto S1600+. These systems will increase data rates to 1Gb/s and beyond, providing a network for high-speed multimedia applications and allowing high-resolution monitors in the vehicle to become a reality.

Molex is among those connector manufacturers working to provide NAT segments with industrial data bus solutions and advanced automotive high-speed connectivity. One thing is certain when it comes to vehicle data bus solutions: There is a great deal of exciting interconnect innovation still to come.