MSS54 LCAN K_CANMESSx = 1 DBC

[Niklas]

Hi everyone,
I’ve taken a look at the MSS54 and almost completely disassembled the LCAN. Attached is the CAN DBC file for K_CANMESSx = 1 and 0x7xx IDs; it contains a lot of useful data. The 0x70x IDs (K_CANSEGMx = 1) are incomplete. The DBC is in German, so use a translator :-)

Happy logging!

[karter16]

Nice work - it's worth noting as well that MESS1 and MESS2 have a different payload if the DME is in test bench mode:

MESS1 (cfg.betriebsmode == 1)

Byte 0: n40
Byte 1: rf
Byte 2: mil_st
Byte 3: pwg
Byte 4: zustand_motor
Byte 5: ti_vorst
Byte 6: ti1
Byte 7: ti5​

MESS2 (cfg.betriebsmode == 1)

Byte 0: tz0
Byte 1: tz1
Byte 2: tz2
Byte 3: tz3
Byte 4: tz4
Byte 5: tz5
Byte 6: kr_dtz_sum
Byte 7: ka_dtz_sum;

For SEGM1 byte 7 is multiplexed:

SEGM1

Byte 0: Cylinder number (lu_zyl + 1)
Byte 1: lu_sta LSB
Byte 2: lu_sta MSB
Byte 3: lu_dyn LSB
Byte 4: lu_dyn MSB
Byte 5: lu_kru LSB
Byte 6: lu_kru MSB
Byte 7, Cylinder 1: tz_zkue_diag
Byte 7, Cylinder 2: n40
Byte 7, Cylinder 3: lu_st
Byte 7, Cylinder 4: rf >> 3
Byte 7, Cylinder 5: lu_kru_tp (capped at 255)
Byte 7, Cylinder 6: lu_idle_trigger

Likewise for SEGM2

SEGM2

Byte 0: Cylinder number (lu_zyl + 1)
Byte 1: lu[lu_zyl] LSB
Byte 2: lu[lu_zyl] MSB
Byte 3: lu_ts LSB
Byte 4: lu_ts MSB
Byte 5: lu_schwelle LSB
Byte 6: lu_schwelle MSB
Byte 7, Cylinder 1: lu_merk_ti_done
Byte 7, Cylinder 2: n40
Byte 7, Cylinder 3: lu_st
Byte 7, Cylinder 4: rf >> 3
Byte 7, Cylinder 5: v (capped at 255)
Byte 7, Cylinder 6: lu_aus_zyl

[Bry5on]

Awesome. I've set a byte in my DME to log knock over CAN, which nets the following:

0x700 & 0x701
byte 0 = sounds like you've got cylinder ID right, where 0x700 is cyls 1-3 and 0x701 is cyls 4-6
byte 1 is knock retard for that cylinder - to get into degrees, divide by 10
bytes 2-3 are little endian u16 knock amplitude for that cylinder. I'm not sure what this scaling should be, I don't scale it for my uses
byte 4 seems to be a smoothed knock value
bytes 5+ I'm not sure

Hope this helps, as I don't have an SMG to test or validate against and I'm not sure if they're the same. On the left side of this image you can see how I sanitize these values by cylinder and datalog them continuously.

[karter16]

Awesome. I've set a byte in my DME to log knock over CAN, which nets the following:

0x700 & 0x701
byte 0 = sounds like you've got cylinder ID right, where 0x700 is cyls 1-3 and 0x701 is cyls 4-6
byte 1 is knock retard for that cylinder - to get into degrees, divide by 10
bytes 2-3 are little endian u16 knock amplitude for that cylinder. I'm not sure what this scaling should be, I don't scale it for my uses
byte 4 seems to be a smoothed knock value
bytes 5+ I'm not sure

Hope this helps, as I don't have an SMG to test or validate against and I'm not sure if they're the same. On the left side of this image you can see how I sanitize these values by cylinder and datalog them continuously.

Correct me if I'm wrong but I think you're talking about 0x700 and 0x701 on the Master CAN bus yeah? What Niklas is refering to is messages on the Slave (SMG) CAN bus, which happen to use the same 0x700 and 701 ARBIDs but have different contents (Misfire detection).

[Bry5on]

Correct me if I'm wrong but I think you're talking about 0x700 and 0x701 on the Master CAN bus yeah? What Niklas is refering to is messages on the Slave (SMG) CAN bus, which happen to use the same 0x700 and 701 ARBIDs but have different contents (Misfire detection).

Whoops. Yeah, color me an SMG newbie then.