Documentation of the SCN format

[topkekega]

Recently while working on a project i came across a document in WIS/ASRA which describes the SCN format, since you've mentioned it in the readme i thought i'll share: https://imgur.com/a/9OeMiL8

Note that i'm not a native english speaker, but i'll try my best to translate this:

The Software Calibration Number (SCN) is legally required for all exhaust gas relevant control units in europe and the USA starting from model year 2002. All software and Codings of a control unit need to be uniquely identifiable using the SCN. The SCN is a 16 digit number. The first 10 digits are the part number (usually the part number of the control unit software). The next 2 digits describe the factory or outside organization (?) in which the vehicle has been coded. The next 4 digits are a counter of the variants of the coding string of the vehicle specific build state. This number is incremented every time a different coding string is created.

In case non standard / special parts are added or removed to/from the vehicle (e.g. adding an aftermarket phone), these codings have to be written into the central system before requesting them. For this the responsible government organisation (MPC) has to be contacted.

[jglim]

Hey topkekega and thanks for making time to create this issue with a good translation.

My concern on the SCN stems from the scary warning message that Vediamo displays when one is about to write a new variant-coding string onto an ECU. Based on your explanation, the SCN will indeed be invalidated after changing any fields of a variant string (as designed). The possibility of cloning a different target's variant coding will probably still work if the target's SCN is also copied together.

Your explanation was very helpful -- thanks again!