Method for ascertaining the control unit temperature by means of a time synchronization protocol

1 . A method for ascertaining a temperature of a control unit in a motor vehicle by means of Ethernet, the method comprising:

determining a delay time of a first signal on a first connecting path between a first server ECU of the Ethernet onboard network and a second server ECU of the Ethernet onboard network;

determining a maximum speed of the first connecting path on the basis of the delay time; and

identifying at least the first server ECU of the Ethernet onboard network;

synchronizing at least the first server ECU of the Ethernet onboard network;

ascertaining a synchronization interval;

ascertaining a timestamp of the first server ECU;

reading a timestamp or querying a time of the first server ECU;

comparing the timestamp with a reference clock of the Ethernet onboard network;

carrying out a delay time measurement;

ascertaining a speed of the associated clock generator;

ascertaining a time difference of the synchronization interval;

ascertaining a last synchronization;

reference measurement of a clock rate of a clock generator of the first server ECU with respect to a clock rate of a clock generator of the second server ECU;

monitoring the clock rate of the clock generator of the first server ECU and the clock rate of the clock generator of the second server ECU;

ascertaining a first server ECU temperature and a second server ECU temperature;

ascertaining an ECU temperature change of the first server ECU and/or the second server ECU by evaluating the reference measurement, by way of determining at what frequency of the clock generators the ascertained server ECU temperatures are present.

2 . The method as claimed in claim 1 , wherein the reference measurement of a clock rate of the first server ECU and the second server ECU are ascertained by means of the IEEE 802.1AS protocol.

3 . The method as claimed in claim 1 , wherein the speed of the clock generator is ascertained by the PTP NRR (Neighbor Rate Ratio) method.

4 . The method as claimed in claim 1 , wherein the following steps are carried out:

the NRR is continuously ascertained and/or monitored,

the delay time measurement is carried out,

the NRR is logged,

the newly recorded NRR is compared with the stored values,

wherein a check is made to establish whether the NRR is greater than the last value and, if a greater value of the NRR is present, the factor by which the NRR is greater than the last value of the NRR is checked and then the temperature increase is calculated and, if an NRR value that is less than the last value is present, then a temperature decrease is calculated.

5 . The method as claimed in claim 1 , wherein the type of the transmission medium and the ascertainment of the synchronization interval

ascertainment of a drift of a timer of the first control unit

ascertainment of a timestamp of the first control unit

ascertainment of the speed of the associated clock generator

ascertainment of the time difference of the synchronization interval

ascertainment of the last synchronization

are communicated to a program in the Ethernet onboard network and a connecting path selection of the program is adapted on the basis of the type of the transmission medium.

6 . The method as claimed in claim 1 , wherein the type of the transmission medium and the

ascertainment of the synchronization interval,

ascertainment of a drift of a timer of the first control unit,

ascertainment of a timestamp of the first control unit,

ascertainment of the speed of the associated clock generator,

ascertainment of the time difference of the synchronization interval,

ascertainment of the last synchronization,

are communicated to a program in the Ethernet onboard network and a connecting path selection of the program is adapted on the basis of the type of the transmission medium.

7 . The method as claimed in claim 1 , wherein the type of the transmission medium is determined as optical, copper or wireless.

8 . The method as claimed in claim 1 , wherein a transmission security value, which describes a probability of loss of data transmitted by way of the first connecting path, is assigned to the first connecting path ( 6 ) on the basis of the type of the transmission medium.

9 . The method as claimed in claim 1 , wherein delay times of a plurality of signals on the first connecting path are determined and the fastest delay time of the plurality of signals is selected, the maximum speed of the first connecting path being determined on the basis of the fastest delay time.

10 . The method as claimed in claim 1 , wherein a delay time of a second signal on a second connecting path, which is different from the first connecting path, between the first control unit and the second control unit is determined, and a maximum speed of the second connecting path is determined, a type of the transmission medium of the second connecting path being determined on the basis of the maximum speed of the second connecting path.

11 . The method as claimed in claim 1 , wherein the method is performed after the first control unit changes from a normal operating mode to an energy-saving mode and/or from the energy-saving mode to the normal operating mode.

12 . The method as claimed in claim 1 , wherein the delay time of the first signal is determined using the first control unit and a delay time of a third signal on a third connecting path, which is connected to the first control unit only indirectly, between the second control unit and a third control unit of the Ethernet onboard network is determined using the third control unit, the determination of the delay time of the third signal being triggered by a service message sent from the first control unit to the third control unit.

13 . An Ethernet onboard network for a motor vehicle, having a first control unit and a second control unit, wherein the control units are connected to one another by way of at least one connecting path, and the first control unit is in a form as claimed in claim 12 .

14 . A control unit for an Ethernet onboard network, which, as a first control unit, is designed:

to send a signal to a second control unit of the Ethernet onboard network and to receive the signal from the second control unit;

to determine a delay time of the signal on a connecting path to the second control unit;

to determine a maximum speed of the connecting path on the basis of the delay time; and

to determine a type of a transmission medium of the connecting path on the basis of the maximum speed,

and at least includes

a microprocessor,

a volatile memory and nonvolatile memory,

at least two communication interfaces,

a synchronizable timer,

the nonvolatile memory containing program instructions that, when executed by the microprocessor,

wherein at least the method as claimed in claim 1 is implementable and executable.

15 . The Ethernet onboard network as claimed in claim 14 , wherein the Ethernet onboard network comprises 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 connecting path, wherein the third control unit is designed to determine a delay time of a third signal on the third connecting path, wherein the first control unit is designed to trigger the determination of the delay time of the third signal by way of a service message to the third control unit.

16 . A vehicle having multiple control units as claimed in claim 14 , comprising an Ethernet onboard network.

17 . A non-transitory computer program product comprising instructions that, when the program is executed by a computer, cause said computer to perform the method as claimed in claim 1 .

18 . A non-transitory computer-readable medium on which the computer program product as claimed in claim 17 is stored.