[DoCAN] Vehicle Diagnostic Communication Part 44 [UDS 5]

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Introduction.
Routine
Upload/Download
Conclusion

Introduction.

Explanation of ISO 14229, the UDS.
In this article, the following functional units of the UDS will be explained.

Routine
Upload/Download

Routine

This section explains the functional unit called Routine.
There is one type of service included within it.

Service	SID	Description
RoutineControl	$31	Start, stop, and request the result of a routine in the ECU.

It is obvious that this routine is the key point.
What does this routine do?
What exactly is the process?

The answer is “not decided”.

However, if the answer is “not decided,” it is hard to know what it is supposed to do.
Let me tell you about my experience.
A typical example is an online calibration function that is used only during development.
Also, if it is possible, it is likely to be used for logging functions inside ECUs.

In other words, it really could be used for anything.
However, since it is often a function that is different from the purpose of the vehicle, it would be restricted to use only during development or something like that.

It would be good to think that it could do something more special than I/O Control.

Upload/Download

Finally, the Upload/Download functional unit is explained.

Service	SID	Description
RequestDownload	$34	Data transfer negotiation request from the off-board tester to the ECU
RequestUpload	$35	Data transfer negotiation request from the ECU to the off-board tester
TransferData	$36	Data transfer request (both Upload and Download use this SID)
RequestTransferExit	$37	End of data transfer request
RequestFileTransfer	$38	File transfer negotiation request

Although you understand what each of the above says, you are not sure of the specific flow of the request?
Unlike other functional units, this functional unit is a type that combines multiple SIDs to achieve its purpose.

For example, to transfer data from an off-board tester to an ECU, the flow is as follows.
(1) Request to start Download process by RequestDownload
(2) Repeat TransferData to acquire data
(3) RequestTransferExit to terminate the transfer process.

Conversely, in the case of data transfer from the ECU to the off-board tester, it is as follows.
(1) Request to start Upload process with RequestUpload
(2) Repeat TransferData to transfer data
(3) Transfer data by repeating TransferData.

If you have good guesses, you may remember the existence of ReadMemoryByAddress (SID$23) and WriteMemoryByAddress (SID$3D) for reading and writing data.
Are they different from these?

In the sense of simple read/write, they are the same, but they are different in many ways.
Features of the Upload/Download function unit service include the following.

Compression
Encryption

These are used to achieve the following in reprogramming (software updates)

Increase data transfer efficiency
Ensure confidentiality

One service I have not mentioned so far is RequestFileTransfer.
I have never seen it used.
It seems to be used to transfer data in the form of a file, similar to specifying a file path on a PC.
The process flow is the same as the others as follows.

(1) Request file access processing start request with RequestFileTransfer
(2) Repeat TransferData to transfer data
(3) Transfer data is transferred by repeating TransferData.

The read/write switching is specified by a parameter of RequestFileTransfer.

Is the concept of a file used in ECUs?

It cannot be said that it is not used.
There are various types of ECUs, and for example, a telematics unit that communicates wirelessly with the outside world may have such a unit.

At any rate, this is the end of the overview of the services included in each functional unit.

Conclusion

Routine explanation.
- Mainly used for functions such as those used during development.
Explanation of Upload/Download.
- A group of services for data transfer that can also compress and encrypt data.

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