The Background Diagnostic Mode allows a serial data transmission at the same time as the measurement cycle (PDCM) is executed.
The transmission is done in a reserved area seperated for ECU and sensors at the begin of a measurement cycle. Therefore the data rate is reduced by the length of the area.
The data packages of the forward (ECU sensor) and backward (sensor ECU) communication will be split and sent one after the other. That means at first the ECU sends its command split in 2-bit packages before the broadcast command of the PDCM mode will be sent.
After that the activated sensor sends its data package split in one nibble per cycle (4 bit information as described in PDCM mode) at the reserved area before the time slot.
In dependence of the length of the command and response package the transmission of the information needs a multiple of the normal data transmission rate.
