VAG-Com: Baud Rate Sync Issues & Fixes

Good day.

I'm having the following problem. An old adapter based on Jeff's optocoupler design only works with the motor control unit when connected to a USB adapter on my new laptop. While I'm somewhat relieved that at least the most important control unit is responding, it's not enough for me.
When I have all the control units checked for errors one by one, almost all of them report the error message: 'Can't synchronize baud rate.'
Is it possible to calibrate the VAG-COM software with this adapter, or am I stuck with it as is?

Is there currently a schematic diagram available for soldering your own USB-enabled adapter?


Have a nice Sunday still.

muellet2 wrote:

Is it possible to calibrate the VAG-COM software with this adapter, or do I have to live with it as is?

The problem (once again) lies in the minimal opto-circuit design without any possibility of adjustment to specific conditions, which leaves the user vulnerable to image length errors resulting from this design.

If you manage to get that thing working with the VAGCOM adapters (which I doubt), you'll only be masking the underlying problems without actually fixing them -> a stable connection probably wouldn't be possible even then.

I think this problem is more likely due to the USB<->RS232 adapter. Many of them do not support the 'non-standard' baud rates that various control units require.

-Uwe-

Uwe@Ross-Tech wrote:

I think this problem is more likely due to the USB<->RS232 adapter. Many of them do not support the "non-standard" baud rates that are required by various control units at all.

You're right, I had overlooked the part about the USB-to-RS232 adapter.