What more can the VAG1551 do?

Hello,

Although I have extensively read the forums on vehicle management, I still don't know whether I can manage my vehicles or not. Only a fraction of the vehicles are marked with 'Yes' in the compatibility list of the Vehicle Explorer.
To the best of my knowledge, there is a VAG 1551 measuring device in the workshops. It has been used for years to measure all types of vehicles from VW, Seat, and Audi.
Which standards are supported by the VAG 1551 (OBD I and OBD II)?
Some of the vehicles are likely compatible from the mid-90s onwards. Which company established this standard (Bosch?)? How can I identify the compatibility based on the components?
I suspect that there are several different connection cables for the VAG 1551, designed for various vehicles. As far as I know, these cables only adapt to the different pin configurations and provide electrical isolation. The communication protocols must be built into the VAG 1551 itself.
Can someone clarify this?

Hello Andreas,
The VAG testers 1551 and 1552 (a smaller version of the 1551 without a printer) are primarily testing devices from/for the VAG group.
They support the company's specific requirements for vehicle diagnostics.
They are comparable to VAG-COM in terms of functionality. Standardized OBD functions are not really supported.
There are only two connection cables for the devices. In newer vehicles, the 16-pin OBD2 connector is used, while in older vehicles, the diagnostic cable terminates in three ends, which are either single-pole or double-pole.
The connector pins provide 12V, ground, K-line, L-line, and (for older control units) turn signal evaluation.
Extensions for CAN or RS422 are available, but they are quite rare.

Best regards, Rudi.