![[DoCAN] Vehicle Diagnostic Communication Part 6 [ISO-TP 2]](https://www.simulationroom999.com/blog/wp-content/uploads/2022/11/01_eyecatch-2.png)
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https://www.simulationroom999.com/blog/diagnostic-communication-en-back-issue/
Introduction.
This is a continuation of the explanation of the network layer of vehicle diagnostic communication.
The addressing format will be explained from this time on.
Types of addressing formats
The four types of addressing formats described in the previous issue are listed again.
- Normal Addressing
- Normal fixed addressing
- Extended addressing
- Mixed addressing
This is not explained in much depth in Vector’s ” Beginning Diagnostics”.
Similarly, there is no mention of ISO 15765-2 in the Wikipedia entry.
There are only a limited times when we need to be concerned about these aspects, and the granularity with which this section is discussed in detail would be too much information, so we are probably avoiding describing them.
The parameters that are part of the addressing format should also be reiterated.
| Name | Description |
|---|---|
| N_AI | network address information |
| N_TAtype | network target address type |
| N_TA | network target address |
| N_SA | network source address |
| N_AE | network address extension |
Normal Addressing
This will be the simplest format.
| CANID | DataField |
|---|---|
| N_AI | – |
In other words, the CANID itself determines the destination and source.
The destination and source cannot be determined by looking at this N_AI alone, but must be defined as a manufacturer’s network specification.
For example
0x111 is ECU_A from the off-board tester.
0x222 is from ECU_A to the off-board tester.
0x999 is the functional address to all ECUs.
The above is how it is defined.
It is not as versatile as Ethernet, but it is simple, easy to understand, and easy to define.
Therefore, this addressing format is one in which simplicity is important.
Normal fixed addressing
Normal fixed addressing consists of the following.
| CANID | DataField | |||
|---|---|---|---|---|
| 24-28[bit] | 16-23[bit] | 8-15[bit] | 0-7[bit] | 1byte~ |
| 0x18 | N_TAtype | N_TA | N_SA | – |
The CANID will be a 29-bit ID, that is, an extended ID.
And N_TAtype is switched by
- If 0xDA, it is a physical address
- If 0xDB, it is a functional address.
N_TA and N_SA are determined by the manufacturer’s network specifications.
However, the range for off-board testers is 0xF1 to 0xFD.
Each ECU also has a specific range of numbers to be set for each area in the SAE standard.
SAE International, formerly named the Society of Automotive Engineers, is a United States-based, globally active professional association and standards developing organization for engineering professionals in various industries. SAE International’s world headquarters is in Warrendale, Pennsylvania, 20 miles north of Pittsburgh, Pennsylvania. Principal emphasis is placed on global transport industries such as aerospace, automotive, and commercial vehicles. The organization adopted the name SAE International to reflect the broader emphasis on mobility.
Wikipedia(https://en.wikipedia.org/wiki/SAE_International)
This addressing format is characterized by the fact that it is easy to define a very clear network specification.
That may be why the keyword “Fixed” is used.
Conclusion
- Normal addressing is the simplest addressing format.
- Normal fixed addressing is the easiest addressing format to define as a specification.
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