Network Management

Within a CANOPEN network, only one NMT master exists (NMT = Network management). All other modules are NMT slaves. The NMT master completely controls all modules and is able to change their states. The following states are distinguished:

Initialization

After switching-on, a node is first in the initialization state. During this phase, the device application and the device communication are initialized. Furthermore, a so-called boot-up message is transmitted by the node to signalize its basic readiness for operation. After this phase is finished, the node automatically changes to the pre-operational state.

Pre-operational

In this state, communication with the node is possible via Service Data Objects (SDOs). The node is not able to perform PDO communication and does not send any emergency messages.

Operational

In this state, SDO and PDO communication is possible. The access to the Object Directory via the SDO protocol depends on the device implementation and may be restricted

Stopped

In the stopped state, a node is completely disconnected from the network. Neither SDO communication nor PDO communication is possible. A state change of the node can only be initiated by a corresponding network command (e.g. Start Node).