Suppose all nodes in a CAN network are configured using acceptance filters to rx packets that are addressed only to them. Example: Node A configured to rx packets addressed only to "A" in the 11-bit ID field and so on.
Scenario: If there are four nodes, A, B, C, and D.
Question 1: If A addresses a packet to E (not a valid ID), will node A's ACK flag be set indicating that a message has been acknowledged by a node? That is, if a message is not accepted by an acceptance filter, will, whether a message has been rxd or not be known to the sender.
Question 2 (depends on question 1): If A addresses a packet to D (valid ID), does acknowledgement of the message indicate that only D has successfully received the message? Or, does it mean that all nodes received the message though their acceptance filters are configured to rx only their specific IDs?
Best Answer
ACK only means that the raw message was received intact. There were no timing violations that would cause a message to not be detected, and the checksum matched. Filters work at a higher level.