With a properly set up CAN bus messages are acknowledged by the receiver. This is in the CAN specification.
If the CAN bus is set up properly (termination and receiver), messages are acknowledged by the receiver, and AIM values updated properly.
- if the CAN bus is NOT set up properly, it will not work (resend is done by the sender, possibly forever, if no ACK - with oldest fw apparently frozen old values that do not update: Only happens with incorrect setup: CAN-bus without any receiver that acknowledges messages ).
- with old versions of AIM to CAN firmware kept resending the old message. If the bus got fixed, messages acknowledged, it just worked (AIM values were updating, of course).
- This changed appr. 2019-12 so even with an inoperational CAN bus and infinitely repeating the sent messages, fresh data is sent, updated quickly.
- No significance if the CAN-bus is operational and the receiver Acknowledges the messages.
- Note: with aim2can welcome message (capture from serial 19200,8n1 on powerup) is the only practical way to check fw version
Solution: to make it work, set up the CAN-bus properly
- proper termination
- receiver should ACK the messages
- or the sniffer can be configured to ACK messages (sniffers might default to be non-intrusive)
- if the sniffed data appears to be frozen, NOT updating, fix the communication. With good RS232 and CAN-bus it will just work, and update continuously.
See also