Help Writing a CAN Packet to a Lambda Controller Please.

Hey Guys,

I need a little help to understand how to write a CAN packet to a Lambda module i have purchased. Still trying to get my head around writing custom CAN packets.

I have attached the instructions of the device and I am trying to write the message via a Plex Knock V3 Tx template (attached a draft template) but are having a hard time interpreting the information and converting it to a usable hex value.

In their own worked example (as attached) they have specified a Motec dataset in Byte 3 as being 0x01 hex or 1 in decimal but there instructions mention in Byte 3 Bits 0-3 that Motec LTC = 0 , wouldn't it be 0x00 ?? (note: bits 4-7 are reserved and they should be 0)

Byte 4 is for the Lambda sensor type:

Ch 1 - Byte 4 (bits 0-3)

0 = LSU4.9

1 = LSU4.9 ADV

Ch 2 – Byte 4 (bits 4-7)

0 = LSU4.9

1 = LSU4.9 ADV

In the example given they used:

Ch1 as a LSU4.9 and Ch2 as a LSU4.9 ADV and the hex value came to = 0x21 or 33 in decimal? which has confused me on how it worked out to be this value.

Say if I was to give a few examples of different setups, is someone able to explain to me on how to work it out, so i get a better understanding please?

Example 1 : Haltech dataset and using 2 x LSU4.9 ADV what would be the hex values be for byte 3 and byte 4 ?

Example 2 : Motec dataset and have 2 x LSU4.9 sensors what would be the hex values for byte 3 and byte 4 ?

Example 3 : Link ECU dataset and have a LSU4.9 ADV on Ch1 and a LSU4.9 on ch2 what would be the hex value for byte 3 and byte 4?

Hope that makes sense and any help would be greatly appreciated.

Thanks.

Well, their instructions and sample are in disagreement. I would contact the MFG and ask which is correct -- is MoTeC OEM=1 or OEM=0? LSU4.9=1 or LSU 4.9=0? My bet, they have bumped all the values up by 1, and are using 0 to signify no change. They fixed the example to reflect this, but they didn't update the documentation.

Their instructions seem pretty clear. Assuming the documentation (not the example) is correct then for

Haltech, 2x LSU ADV you would set byte3 to 0x01, and byte 4 to 0x11

Motec, 2x LSU 4.9, you would set byte3 to 0x00 and byte 4 to 0x00

Link CAN Lambda, ch1=LSU ADV and ch2 LSU 4.9, you would set byte3 to 0x02 and byte 4 to 0x01

If I am correct about the change to use 0 to indicate no change, then the values would be as follows:

Haltech, 2x LSU ADV you would set byte3 to 0x02, and byte 4 to 0x22

Motec, 2x LSU 4.9, you would set byte3 to 0x01 and byte 4 to 0x11

Link CAN Lambda, ch1=LSU ADV and ch2 LSU 4.9, you would set byte3 to 0x03 and byte 4 to 0x12

Thanks for that David, i thought i was missing something but that makes sense. I did try to contact the manufacturer but they haven't replied yet. I will try to contact them again. Many thanks again.