[Dcm] Vehicle Diagnostic Communication Part 84 [Simulation 23]

Click here for back issues.
https://www.simulationroom999.com/blog/diagnostic-communication-en-back-issue/

Introduction.
Special specifications for NRC
Result of simulation of special behavior (message)
Results of simulation of special behavior (CAN lines)
What is DslDiagRespMaxNumRespPend?
Conclusion.

Introduction.

Explanation of the AUTOSAR-Dcm simulation.
This is an extra installment of the explanation of the WriteDataByIdentifier simulation.

Special specifications for NRC

NRC$78 appeared in the last WriteDataByIdentifier.
We will check the special behavior of that one.
First, we show the behavior.

Result of simulation of special behavior (message)

The message communicated is as follows.

Send msg : 1003 // Transition to extendDiagnosticSession
Recv msg : 500300300064
Send msg : 2713 // Seed request
Recv msg : 6713deadbeef
Send msg : 2714deadbeef // send key
Recv msg : 6714
Send msg : 2e567811223344 // Write to DID=5678
Recv msg : 7f2e78 // NRC$78(ResponsePending)
Recv msg : 7f2e78 // NRC$78(ResponsePending)
Recv msg : 7f2e10 // NRC$10(generalReject)
Exiting

Results of simulation of special behavior (CAN lines)

And the CAN line log is as follows.

Begin Triggerblock
 0.000000 Start of measurement
 
 // Transition to extendDiagnosticSession
 0.000000 1  18DA10F1x       Rx   d 8 02 10 03 CC CC CC CC CC
 0.001884 1  18DAF110x       Rx   d 8 06 50 03 00 30 00 64 55
 
 // Seed Request
 0.005841 1  18DA10F1x       Rx   d 8 02 27 13 CC CC CC CC CC
 0.007823 1  18DAF110x       Rx   d 8 06 67 13 DE AD BE EF 55
 
 // Key Sending
 0.011862 1  18DA10F1x       Rx   d 8 06 27 14 DE AD BE EF CC
 0.013787 1  18DAF110x       Rx   d 8 02 67 14 55 55 55 55 55
 
 // Write to DID=5678
 0.017834 1  18DA10F1x       Rx   d 8 07 2E 56 78 11 22 33 44
 0.066617 1  18DAF110x       Rx   d 8 03 7F 2E 78 55 55 55 55
 1.066197 1  18DAF110x       Rx   d 8 03 7F 2E 78 55 55 55 55
 2.067071 1  18DAF110x       Rx   d 8 03 7F 2E 10 55 55 55 55
End TriggerBlock

It shows a state that is extending to P2* time using NRC$78 in WriteDataByIdentifier.
However, if look closely, there is an NRC$10 (generalReject) at the end.
What is the situation with this?

For example, what do you think happens if NRC$78 is returned infinitely?
If it is in accordance with the specification, it would wait indefinitely.
Is this not a problem for the specification?

Infinite would be bad indeed.
This is where DslDiagRespMaxNumRespPend comes in.

What is DslDiagRespMaxNumRespPend?

DslDiagRespMaxNumRespPend defines the upper limit of the number of times NRC$78 is returned.
In other words, NRC$10 is to be returned when this limit is exceeded.
This is an AUTOSAR-Dcm specification that is not specified in ISO14229-1.

Can it be specified in AUTOSAR-Dcm if it is not specified in ISO14229-1?
Even though it is not specified in ISO14229-1, it is actually a specification that is often specified by manufacturers.
AUTOSAR also has two aspects: one is to comply with the standard, and the other is to incorporate the de facto standard of the manufacturer.

Conclusion.

We saw a pattern of returning NRC$10 (generalReject) when NRC$78 (ResponsePending) exceeds a certain number of times.
This specification is not specified in ISO 14229-1.
However, it is likely to be a de facto standard.
- Therefore, it is assumed that it is incorporated as an AUTOSAR specification.

Click here for back issues.