SAE J1979/ISO 15031-5 set includes the communication between the vehicle’s OBD systems and test equipment implemented across vehicles within the scope of the legislated emissions-related OBD.

To achieve this, it is based on the Open Systems Interconnection (OSI) Basic Reference Model in accordance with ISO/IEC 7498-1 and ISO/IEC 10731, which structures communication systems into seven layers. When mapped on this model, the services specified are broken into:

1. — Diagnostic services (layer 7), specified in:

   1. — ISO 15031-5/SAE J1979 (emissions-related OBD),

   2. — ISO 27145-3 (WWH-OBD),

2. — Presentation layer (layer 6), specified in:

   1. — ISO 15031-2, SAE J1930-DA,

   2. — ISO 15031-5, SAE J1979-DA,

   3. — ISO 15031-6, SAE J2012-DA,

   4. — ISO 27145-2, SAE J2012-DA,

3. — Session layer services (layer 5), specified in:

   1. — ISO 14229-2 supports ISO 15765-4 DoCAN and ISO 14230-4 DoK-Line protocols,

   2. — ISO 14229-2 is not applicable to the SAE J1850 and ISO 9141-2 protocols,

4. — Transport layer services (layer 4), specified in:

   1. — DoCAN: ISO 15765-2 Transport protocol and network layer services,

   2. — SAE J1850: ISO 15031-5/SAE J1979 Emissions-related diagnostic services,

   3. — ISO 9141-2: ISO 15031-5/SAE J1979 Emissions-related diagnostic services,

   4. — DoK-Line: ISO 14230-4, ISO 15031-5/SAE J1979 Emissions-related diagnostic services,

5. — Network layer services (layer 3), specified in:

   1. — DoCAN: ISO 15765-2 Transport protocol and network layer services,

   2. — SAE J1850: ISO 15031-5/SAE J1979 Emissions-related diagnostic services,

   3. — ISO 9141-2: ISO 15031-5/SAE J1979 Emissions-related diagnostic services,

   4. — DoK-Line: ISO 14230-4, ISO 15031-5/SAE J1979 Emissions-related diagnostic services,

6. — Data link layer (layer 2), specified in:

   1. — DoCAN: ISO 15765-4, ISO 11898-1, -2,

   2. — SAE J1850,

   3. — ISO 9141-2,

   4. — DoK-Line: ISO 14230-2,

7. — Physical layer (layer 1), specified in:

   1. — DoCAN: ISO 15765-4, ISO 11898-1, -2,

   2. — SAE J1850,

   3. — ISO 9141-2,

   4. — DoK-Line: ISO 14230-1,

in accordance with Table 1.