Can mapping question
Posted: Wed Jun 22, 2022 6:31 am
Hi guys this will be an easy question for someone but
can messages are still a minefield in my brain not helped by the fact they are sometimes in hex, decimal etc, it makes my brain hurt and want to go back to welding something.
Anyway I’m trying to send out from the vcu the motor rpm to the RX8 can bus this info is needed importantly to start the PAS and run the Rev counter,
All information I’ve found indicates that the message needs to be sent to address 0x201 (513) and is determined by
Rpm x 3.85 with the resulting value is split across 2 8bit values highbyte to byte 0 and low byte to byte 1.
Now I presume as it wants to 2 separate 8bit values to work that this isn’t possible via the can mapping as I can only map one message per spot value and I can’t sent it a 16 but value starting at byte 0 because that’s a different format to the 2 8bit values it wants, this is where my head starts to hurt,
Im thinking I need to add another device on my can bus, send a can message for rpm to that from the vcu and have it spit it back out in the correct format for the car, this is the route I’ll be perusing unless anyone can see through the stupid and tell me stop your doing it wrong!
can messages are still a minefield in my brain not helped by the fact they are sometimes in hex, decimal etc, it makes my brain hurt and want to go back to welding something.
Anyway I’m trying to send out from the vcu the motor rpm to the RX8 can bus this info is needed importantly to start the PAS and run the Rev counter,
All information I’ve found indicates that the message needs to be sent to address 0x201 (513) and is determined by
Rpm x 3.85 with the resulting value is split across 2 8bit values highbyte to byte 0 and low byte to byte 1.
Now I presume as it wants to 2 separate 8bit values to work that this isn’t possible via the can mapping as I can only map one message per spot value and I can’t sent it a 16 but value starting at byte 0 because that’s a different format to the 2 8bit values it wants, this is where my head starts to hurt,
Im thinking I need to add another device on my can bus, send a can message for rpm to that from the vcu and have it spit it back out in the correct format for the car, this is the route I’ll be perusing unless anyone can see through the stupid and tell me stop your doing it wrong!