[Dcm] Vehicle Diagnostic Communication Part 63 [Simulation 2]

[Dcm] Vehicle Diagnostic Communication Part 63 [Simulation 2] 車両診断通信
[Dcm] Vehicle Diagnostic Communication Part 63 [Simulation 2]

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In this article, I will explain the interface of AUTOSAR-Dcm.

Specification of AUTOSAR-Dcm

As with AUTOSAR-CanTp, we should first understand the AUTOSAR-Dcm interface.
Since OpenSAR is r3.x, you should read the AUTOSAR-Dcm specification for r3.3.

Currently, old versions of the AUTOSAR classic platform can no longer be downloaded. Therefore, it is temporarily placed here.

Interfaces for AUTOSAR-Dcm

I have extracted the necessary interfaces.
The following five are them.

  • Dcm_ProvideRxBuffer
  • Dcm_RxIndication
  • PduR_DcmTransmit
  • Dcm_TxConfirmation
  • Dcm_MainFunction

You probably thought it was less than you thought.
These are only interfaces for communication.
The problem with AUTOSAR-Dcm is the number of configuration parameters.

Explanation of the AUTOSAR-Dcm interface

I will explain the previous interface as follows.

Dcm_ProvideRxBufferRequest for buffer to be used by the transport layer when FirstFrame or SingleFrame is received.
Dcm_RxIndicationMessage reception completion notification. (After receiving SingleFrame/ after receiving the last consecutive frame)
PduR_DcmTransmitRequest for transmission from the Dcm to the transport layer; in the case of NRC$78, multiple transmission requests are generated.
Dcm_TxConfirmationMessage transmission completion notification.
Dcm_MainFunctionMain loop. Must be called periodically.

It looks surprisingly normal in this way.
This is because the pure protocol part has been absorbed by CanTp.

However, the explanation of PduR_DcmTransmit is a bit fuzzy.
You can assume that this is simply for NRC$78 handrigs.

AUSOTAR-CanTp only supports sending and receiving messages in accordance with ISO 15765-2.
NRC$78 is designed in accordance with AUTOSAR-Dcm, or ISO14229-1.
Therefore, it is required to be handled on the AUTOSAR-Dcm side, which is higher than AUSOTAR-CanTp.

Well, NRC$78 is a special response message, but it is just a SingleFrame as AUSOTAR-CanTp or ISO15765-2.
Therefore, multiple responses are generated for ISO14229-1 reasons, which is how ISO15765-2 behaves from its standpoint.
In other words, it is the division of responsibility due to the layered structure.

You probably wished I had explained this in a diagram….
I’ll try to have one ready by next article….


  • Check AUTOSAR-Dcm specification (r3.3).
  • Check AUTOSAR-Dcm interface.
  • NRC$78 is just SingleFrame as AUTOSAR-CanTp.

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