CAN allows for data packets with a payload of up to 8 bytes, to send messages longer than 8 bytes it is necessary to use a transport protocol. The OBD-II specification for example makes use of ISO-TP (ISO 15765-2). Volkswagen however uses it's own transport protocol in its vehicles, known as VW TP 2.0.
This is a quick write-up of my understanding of the DTCs and switches in the Siemens PPD and SID803/SID803A/SID206 ECUs. I will be working with the PPD SN100L8000000 file from the sample BDM files.
DTC table entries
There is a table in each file which contains Diagnostic Trouble Codes (DTCs). If you view the table in hex you will see they match up with P-Codes i.e. codes for the powertrain.
PPD Maps is open source (GPLv3) software for detecting maps in Siemens ECU dumps. Supported ECUs are PPD, SID206 & SID803A. There is partial support for SID803 and barely working support for SID201
The software will identify the corresponding axes for each map and also give a list of DTC/P-codes. It will also find single byte switches to turn off DTCs
The file must be a full read of the ECU i.e. BDM. A partial read using a tool such as MPPS or similar will not work.