Testing for Series Production
Series production of FlexRay is due to begin soon. To ensure that all components work smoothly with one another, Bosch researchers are developing test procedures and checking the function of individual parts of the system.
Operating a control unit on a FlexRay bus requires two components: a bus transceiver and a communication controller. The transceiver creates the direct connection to the data line. It writes onto the bus, in the form of voltage pulses, the logical information that is to be transferred, and it reads the signals that are transmitted by other control units linked to the bus. These operations take place on what is referred to as the “physical layer.” FlexRay also controls the bus protocol, which determines how the network is started up, how a bus clock is established, and which control units may transmit data at which point in time. The communication controller implements the bus protocol in every control unit: For example, it puts the information to be transmitted into a data package, which it transfers to the bus transceiver at the correct point in time for subsequent transmission.Following the publication of the Version 2.1 FlexRay specification, Bosch’s Automotive Electronics unit developed a communication controller that can be used for numerous applications. This module — known as “E-Ray” — was implemented using the hardware description language VHDL. Semiconductor manufacturers can use this module to produce communication controllers. E-Ray is available on the market and is already being used by seven semiconductor manufacturers under license. Because FlexRay contains a complex protocol, however, the question arose as to whether components available on the market actually correspond to the specifications, and if they would be able to communicate with one another in the vehicle without error or interruption.
In response to this concern, the FlexRay consortium specified a conformance test, which it then implemented at different testing facilities. At these facilities, any manufacturer can have their components checked to see if all the functions described in the specification can actually be performed. Components that pass all of the tests then receive certification that they are in conformance with FlexRay — which is the most important condition for interoperability in vehicles. E-Ray has already successfully passed the test confirming that it conforms to the specifications, which has cleared the way for certified FlexRay-compatible components to be rapidly launched on the market. In order to study FlexRay’s operational behavior in detail, Bosch researchers also have built a demonstration model with four control units. This enables them to examine the voltage pulses that run over the network and also to recreate and test various aspects of the bus protocol.
In response to this concern, the FlexRay consortium specified a conformance test, which it then implemented at different testing facilities. At these facilities, any manufacturer can have their components checked to see if all the functions described in the specification can actually be performed. Components that pass all of the tests then receive certification that they are in conformance with FlexRay — which is the most important condition for interoperability in vehicles. E-Ray has already successfully passed the test confirming that it conforms to the specifications, which has cleared the way for certified FlexRay-compatible components to be rapidly launched on the market. In order to study FlexRay’s operational behavior in detail, Bosch researchers also have built a demonstration model with four control units. This enables them to examine the voltage pulses that run over the network and also to recreate and test various aspects of the bus protocol.
Four control units (above) are linked to one another via bus cables (yellow). The circuit board in the middle is an active star. This structure makes it possible for researchers to try out different topologies, such as a star or linear bus connection of the devices.
