METHOD FOR DETERMINING COMPONENTS OF A SENSOR NETWORK WITHIN AN IN-VEHICLE ETHERNET NETWORK IN A MOTOR VEHICLE
A method for determining components of a sensor network within an Ethernet on-board network in a motor vehicle between at least two ECU nodes and at least one further ECU node. The at least one ECU node responds to a received payload with a payload only after a delay time, the delay time satisfying the condition t BUS ≥t B +(t P +t C ) n, where t B denotes a beacon time of the ECU node, t C denotes the commit time of the further ECU node, t P denotes the maximum payload with the maximum length, and n denotes the number of ECU nodes.
1 . A method for determining components of a sensor network within an Ethernet on-board network in a motor vehicle between at least two ECU nodes and at least one further ECU node, wherein at least one ECU node responds to a received payload with a payload only after a delay time, the delay time satisfies a condition t BUS ≥t B +(t P +t C ) n, where t B denotes a beacon time of the ECU node, t C denotes a commit time of the further ECU node, t P denotes a maximum payload with a maximum length, and n denotes a number of ECU nodes, wherein an ECU node of a bus of the Ethernet on-board network, other than a head node, measures a time length of an unused cycle in which no payload data were sent, with the time length measuring being repeated and verified, and following determination of a pure cycle length T L , which is recognized by transmission of a beacon, a transmission window of an ECU node is used to calculate a number of nodes on the bus, wherein minimum and maximum delays during bus access are ascertained dynamically, without being preconfigured.
2 . The method as claimed in claim 1 , wherein the ECU node of the Ethernet on-board network calculates the time length of an unused cycle, in which no payload were sent, using a transmit opportunity timer, and following calculation of the pure cycle length, which is ascertained by transmitting the beacon at the time t B , the transmission window of the ECU node is used to calculate the number of nodes n that are located in the Ethernet on-board network.
3 . The method as claimed in claim 1 , further comprising
identifying a beginning of a new cycle,
seeking a start time of a second cycle following the new cycle,
checking whether a payload was transmitted between the new cycle and the second cycle and, in the event of a transmission, the second cycle is set to the new cycle, and
dynamically calculating the cycle length T L .
4 . The method as claimed in claim 1 , wherein the number of nodes n of the ECU nodes located in the Ethernet on-board network is formed by a ratio of the cycle length to a value of a transmit opportunity timer, wherein, beforehand, the transmit opportunity timer is queried in order to form the ratio of the cycle length to the value of the transmit opportunity timer.
5 . A control unit for an Ethernet on-board network, which, as a first ECU node,
is configured, as a control unit:
to transmit a signal to a second control unit of the Ethernet on-board network and to receive the signal from the second control unit;
to determine a propagation time of the signal on a connection path to the second control unit;
to determine a maximum speed of the connection path based on the propagation time; and
to determine a type of a transmission medium of the connection path based on the maximum speed,
wherein the control unit comprises:
a microprocessor,
a volatile memory and non-volatile memory,
at least two communication interfaces, and
a synchronizable timer,
wherein the non-volatile memory contains program instructions that, when executed by the microprocessor, cause the microprocessor to perform the method as claimed in claim 1 .
6 . An Ethernet on-board network for a motor vehicle, having a first control unit and
a second control unit, wherein the control units are connected to one another via at least one connection path, and at least the first control unit is configured as claimed in claim 5 .
7 . The Ethernet on-board network as claimed in claim 6 , wherein
the Ethernet on-board network has a third control unit, which is connected to the first control unit only indirectly and is connected to the second control unit directly by way of a third connection path, wherein the third control unit is configured to determine a propagation time of a third signal on the third connection path, and the first control unit is configured to trigger the determination of the propagation time of the third signal by a service message to the third control unit.
8 . A computer program product comprising commands that, when the computer program product is executed by a computer, causes the said computer to perform the method as claimed in claim 1 .
9 . A non-transitory computer-readable medium on which the computer program product as claimed in claim 7 is stored.
10 . A vehicle having an Ethernet on-board network comprising multiple control units, each control unit performing as claimed in claim 5 .