How does the Acknowledgement works in CAN Network !!

In CAN (Controller Area Network) communication, ACK (Acknowledgment) is required but it works differently compared to traditional communication protocols.

Here’s how it works:

1️⃣ ACK Mechanism in CAN

• When a message is transmitted on the CAN bus, all nodes that receive it successfully will send an ACK bit (dominant state) in the ACK slot of the message frame.

• The transmitter checks this ACK bit to confirm that at least one node received the message correctly.

2️⃣ Key Points About ACK in CAN:

✅ ACK is Mandatory: At least one receiving node must acknowledge the message.

✅ No Specific Receiver: Any node that successfully receives the message sends the ACK.

✅ No ACK → Retransmission: If no node sends an ACK (e.g., no receiver is present or all receivers have errors), the sender will retry sending the message.

✅ ACK Does Not Mean Message Processing: The ACK only confirms reception, not whether the receiver has processed the message.

3️⃣ What Happens If There’s No ACK?

• The sender retransmits the message after an error frame and goes into an error handling state.

• If continuous failures occur, the sender may enter bus-off mode, stopping further transmissions.

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