I have gathered the can Data of a Scania G380 Truck using stm32 mcu. there is a problem with DM1 faults. according to j1939-73 when dm1 data length is over than 8 bytes it would be packetized by TP.DT (pgn 0xebff) announced by a TP.CM (pgn 0xecff), but I face with these data, packetized in a strange manner :
18ECFF00 DATA: FF FF 7D 7D FD FF FF FF
18EBFF00 DATA: FF FF 7D 7D 3C FF FF FF
18EBFF00 DATA: FF FF 7D 7D FD FF FF FF
18EBFF00 DATA: FF FF 7D 7D 3C FF FF FF
18EBFF00 DATA: FF FF 7D 7D FD FF FF FF
it seems it doesn't follow the protocol.
another strange problem is that dm1 faults were broadcast in single packet repeatedly instead of being packetized in TP.DT pgn. for example I have this log:
18FECA27 DATA: 00 17 09 07 34 22 74 7D TIME: 425447
18FECA10 DATA: 2F 21 43 3C 37 43 06 55 TIME: 425474
18FECA2F DATA: D1 FF 1F FF FF FF FF FF TIME: 425594
18FECA0B DATA: 38 00 FF FF FF FF 00 00 TIME: 425626
18FECA00 DATA: 00 FB 00 FB 3F FC FF FF TIME: 425634
could anyone help me please?
18ECFF00 DATA: FF FF 7D 7D FD FF FF FF
18EBFF00 DATA: FF FF 7D 7D 3C FF FF FF
18EBFF00 DATA: FF FF 7D 7D FD FF FF FF
18EBFF00 DATA: FF FF 7D 7D 3C FF FF FF
18EBFF00 DATA: FF FF 7D 7D FD FF FF FF
This looks like some garbage/default values. I think Scania is not using DM1 messages to report DTCs over CAN bus.