2020/11/25 06:18:51


I try to receive CAN messages from Volvo/MAN truck/bus. The high speed CAN bus in truck is 250kbit/s, but I from one car I was received valid messages... and from another one no messages was received.
I use SAMV71b microcontroller with 12MHz quartz  mcan 1, and use these settings:


 * change in the conf_clock.h. Below is the default configuration. The
 * time quanta is 30MHz / (5+1) =  5MHz. And each bit is (1 + NTSEG1 + 1 + NTSEG2 + 1) = 20 time
 * quanta which means the bit rate is 5MHz/20=250KHz.
/** Nominal bit Baud Rate Prescaler */
/** Nominal bit (Re)Synchronization Jump Width */
/** Nominal bit Time segment before sample point */
/** Nominal bit Time segment after sample point */

If I try communicate my two CAN module together, the communication is perfect, but from the truck....

Anybody has experience in this theme?

2020/11/25 20:56:43
2020/11/26 03:13:33
What do you mean "I am able to receive messages"?
Are you sending requests and receiving data?
Or simply monitoring the bus?
Do not expect that there is always bus activity in the diagnostic port. Also do not expect that both are using diagnostic on CANBUS, or that CANBUS speed is the same in both trucks.
I'm not sure if it's the same with trucks, but when dealing with older cars you may find that diagnostic run on a different bus (like K-Line) even if canbus is present at the diagnostic port. And in newer ones diagnostic may run on only on ethernet on other pins of the diagnostic port
2020/11/26 07:19:45
I  use a  FMS connector.
And I am monitoring the CANBUS in some new trucks, buses.
Thank You.
© 2021 APG vNext Commercial Version 4.5

Use My Existing Forum Account