Optical communications – Multiplex – Optical local area network
Reexamination Certificate
2000-06-30
2003-11-04
Pascal, Leslie (Department: 2633)
Optical communications
Multiplex
Optical local area network
C398S009000, C398S010000, C398S061000, C398S063000, C398S100000, C362S035000, C362S023000, C362S026000, C362S029000, C701S033000, C701S029000, C701S032000
Reexamination Certificate
active
06643465
ABSTRACT:
The invention relates to a method for checking a ring optical network line for data transmission between a plurality of network subscribers in a motor vehicle.
BACKGROUND OF THE INVENTION
Apart from the known CAN networks for signal transmission, it is known for a network in which the data are transmitted optically to be provided in motor vehicles. This network is constructed as a ring and connects a radio, CD changer, sound amplifier, telephone, mobile telephone and voice control system via an optical databus (D
2
B).
In contrast to previous asynchronous, that is to say event-controlled, data transmission as in the case of the CAN bus, such communication and information systems require synchronous data transmission at higher Baud rates, which can be transmitted using optical signals.
For example, as a network subscriber, the radio can carry out the master function and at the same time be used as a gateway to the internal bus and diagnostic system. The CAN-B interface allows information from the D
2
B system to be transmitted to other systems and, conversely, data to be transmitted from the vehicle to the D
2
B system. Particularly intensive interchange takes place between a combination instrument and the network subscriber having the master function, since the D
2
B components can also be controlled via the steering wheel, and information can be displayed via the combination instrument display.
All the audio signals, such as music or speech, are initially transmitted in digital form from the component which produces them via the D
2
B bus either to the network subscriber having the master function or, possibly, to the sound amplifier, where they are converted into an analogue signal and are reproduced via the vehicle loudspeakers. If a telephone system is installed in a vehicle, this has the advantage that there is no need to fit any additional loudspeakers for hands-free operation.
In contrast to conventional vehicle networking, the system components are not linked to one another in a bus, tree or star structure, but in a ring structure. This means that each ring subscriber receives modulated light via the receiving device, carries out signal preprocessing, and then passes on the signal via the optical output. The advantage in this case is that the ring may have any desired number of components added to it, since the maximum optical power is available at the output of each appliance. Since the data are transmitted optically, this is always done unidirectionally, that is to say only in one direction. Optical transmission advantageously allows problems relating to EMC to be avoided.
The operation of such a ring optical network line is described in detail, for example, in VDI Reports No. 1415, entitled Elektronik im Kraftfahrzeug, Tagung Baden-Baden 8 and 9 October 1998=Electronic systems for vehicles/VDI-Gesellschaft Fahrzeug- und Verkehrstechnik, Düsseldorf: VDI Verlag, 1998 (VDI Reports; 1415) ISBN 3-18-091415-7.
Furthermore, U.S. Pat. No. 4,930,049 discloses an arrangement in which both an electrical control line and an optical control line are arranged in a star arrangement in a motor vehicle. This allows the components in the vehicle to be actuated either by means of an electrical control signal or by means of an optical control signal.
The object of the present invention is to propose a method and an apparatus in order to allow such an optical network line to be checked for possible faults.
SUMMARY OF THE INVENTION
A method according to the invention checks a ring optical network line for data transmission between a plurality of network subscribers in a motor vehicle, wherein one network subscriber carries out a master function, in that apart from the optical network line there is a further communication line which has a star structure and in which the network subscriber having the master function is arranged in the centre of the star structure and is connected directly via the communication line to every other network subscriber, wherein the optical network line is checked by the network subscriber having the master function outputting a start signal to the individual network subscribers via the communication line in a first test step at the start of operation of the optical network line, wherein the individual network subscribers acknowledge the start signal for the network subscriber having the master function via the communication line, wherein, in a second test step after the start signal, the network subscriber having the master function outputs an initialization signal via the optical network line, wherein correct operation of the ring optical network line is identified if the network subscriber having the master function receives a signal which corresponds to a nominal signal via the optical network line within a predetermined time interval.
Thus, first of all, it is advantageously possible to test whether all the network subscribers have a reliable electrical power supply and whether the connection can be set up via the communication line. In the next step, it is then possible to check whether communication can take place via the optical ring line once the other fault sources have been excluded.
The nominal signal may in this case correspond to the initialization signal itself. Thus, in this case and in this test step, the signal is just passed on by the individual network subscribers (possibly amplified) as it was received. It is likewise possible to use the individual network subscribers to change the signal in a characteristic manner, so that correct operation of the individual network subscribers can furthermore be checked.
In general, when interruptions occur in bus systems having a ring structure (for example D
2
B OPTICAL), the entire data flow breaks down. This leads to failure of all the systems on the bus. This now results in the problem that, in contrast to multi-master bus systems (for example CAN), the individual controllers can no longer respond in order to diagnose the fault via the ring optical network line. The present invention thus advantageously allows the location of the fault which may have occurred to be found with comparatively little effort.
In an embodiment of the invention method, a disturbance in the voltage supply to a network subscriber or an interruption in the connection via the communication line from the network subscriber having the master function to the network subscriber is identified if the network subscriber having the master function does not receive any acknowledgement of the start signal by the corresponding network subscriber.
A fault cause can thus advantageously be located.
In a further embodiment of the invention method, a network subscriber sends a fault-tracing signal, which characterizes this network subscriber, via the communication line if it has not received any initialization signal via the optical network line, wherein the network subscriber having the master function identifies a fault which relates to the transmission of an optical signal from the network subscriber which, in the opposite direction to the transmission direction of the signal in the ring optical network line is arranged upstream of that network subscriber which has sent a fault-tracing signal and which, in the transmission direction of the ring optical network line is arranged closest to the network subscriber having the master function, or which relates to reception of an optical signal by the network subscriber which sent the fault-tracing signal and which, in the transmission direction of the ring optical network line, is arranged closest to the network subscriber having the master function, or which relates to the ring optical network line between that network subscriber which, in the opposite direction to the transmission direction of the signal in the ring optical network line, is arranged. upstream of that network subscriber which sent the fault-tracing signal and which, in the transmission direction of the ring optical network line, is arranged closest to the network subscriber having the master function, and to this same ne
Bösinger Marcus
Brandes Jens
Marquardt Dieter
Merget Peter
Petry Franz-Josef
Crowell & Moring LLP
Daimler-Chrysler AG
Pascal Leslie
Phan Hanh
LandOfFree
Method for checking a ring optical network line for data... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for checking a ring optical network line for data..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for checking a ring optical network line for data... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3173884