Node Guarding and Heartbeat

Testing the functionality of a CAN node is particularly required if the node does not continuously send messages (cyclic PDOs). Two mechanisms can alternatively be used to monitor the CANOPEN nodes. When the node guarding protocol is used, the NMT master sends messages to the available CANOPEN slaves which have to respond to these messages within a certain time period. Therefore, the NMT master is able to detect if a node fails. Furthermore, the heartbeat protocol can be used with CANOPEN. In this case, each node automatically sends a periodic message. This message can be monitored by each other subscriber in the network.