After, for example, the latest generation of control devices is used in most current diesel models, it was hardly possible at the beginning to read devices via the OBD interface. It was no longer possible to think of a description of the devices.
If one wanted to circumvent the risky removal and soldering of new building blocks, new devices had to be developed, which made the reading and writing via a so-called BDM interface possible.
Just as with traditional chip tuning, the data are also optimized in this way in the same way.
We generally prefer the OBD or BDM tuning to classic chip tuning. We can clarify the possibilities for your car to choose from.