SCP = Standard Corporate Protocol
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a protocol selection matrix adapter for a vehicle and, more particularly, to a protocol selection matrix adapter for a vehicle that interfaces a host computer to multiple in-vehicle networks in a vehicle.
2. Discussion of the Related Art
Vehicles employ various networks and systems for diagnostics, analysis and monitoring of certain vehicle systems. These networks can be integrated with a host computer outside of the vehicle for data acquisition, computer-based measurements, automation systems, etc. with vehicle communications and systems.
These various vehicle systems and networks operate under different protocols. Thus, the various vehicle systems and networks may not be compatible with the host computer. Manufacturers of various systems have addressed this capability problem by using an interface box to talk to multiple data links that are customized to a specific product. However, these types of in-vehicle networks have been expanded to included boats, motorcycles, agricultural equipment, construction equipment, military combat systems, etc. Thus, the existing box used to talk to the multiple data links do not provide a very satisfactory solution to this in-vehicle extension. Further, the trend for vehicles is to have multiple networks on the vehicle.
A protocol selection matrix adapter is needed that automatically interfaces multiple in-vehicle networks to a host computer simultaneously for several protocols, and provides a flexible method to reprogram nodes on the in-vehicle networks.
CAN = Controller Area Network
(Controller Area Network bus) A rugged, digital serial bus designed for industrial environments. Introduced by Bosch in the mid-1980s for in-vehicle communications, it is used in myriad applications including factory automation, building automation, aircraft and aerospace as well as in cars, trucks and buses. CAN bus replaced bulky wiring harnesses with a two-wire differential cable (the two wires carry inverted voltages to decrease interference).
CAN provides services at layers 1 and 2 of the OSI model and uses a broadcast method for placing frames on the wire somewhat similar to Ethernet. Bus distance is based on speed, ranging from a maximum of 40 meters at 1 Mbps to a maximum of six kilometers at 10 Kbps. At speeds up to 125 Kbps, CAN provides fault tolerance. If one of the two wires is cut or shorted, the other keeps transmitting.
In a vehicle, both low- and high-speed CAN buses are used. For example, window, lighting and seat control only need low speeds, while engine, cruise control and antilock brakes require high speeds. Two or three CAN buses may be used in a vehicle; for example, a high-speed bus may be dedicated only for safety (air bags, seat belt tensioners, etc.).
The Bus Hampers After-Market Installations
The CAN bus has made it challenging to add certain after-market products to a vehicle. In older cars, there were discrete wires for everything, but CAN bus signals are digital frames that have to be analyzed to determine their purpose. For example, taxi meters and many GPS navigation systems need to monitor vehicle speed. If speed pulse is no longer available as a discrete wire, a CAN bus interface, such as the CANM8-NAV unit from Bridgewater Electronics (Welcome - Bridgwater Electronics Somerset | Car Alarms.
), can convert speed pulse frames to a speed pulse signal.
CANopen and CiA
Introduced in 1995, CANopen is a high-level application layer protocol that provides services for processes, data and network management. The international organization that governs the CANopen protocol is CAN in Automation (CiA). For more information, visit CAN in Automation (CiA): Controller Area Network (CAN)