Node is any device in the CAN BUS. Each CAN message has a number of parts. The identifier is used to indicate either the sender or the purpose. Every node send and receive message. How do nodes decide whether to do the work according to message or to ignore the message?
CAN Controllers have a mask and match feature. They apply a mask to the identifier field (11 bits standard frame or 29 bits extended frame). After the mask is applied they compare the result to a match register. If there is a match the frame is accepted for further processing, if there is no match then the frame is ignored. N.B. Even in the no match case the hardware still looks at all the bits and will "throw" an error frame if anything is amiss.
