Network components

Ethernet POWERLINK uses a mixture of polling and time-slot techniques. A master, the Managing Node (MN), organizes the structured polling of the stations, the Controlled Nodes (CNs). The master sends a station a PollRequest, which is answered by the station with a PollResponse. A defined time is provided for the PollResponse so that no collisions occur. In a bus cycle, all stations are polled one after the other.

The stations are identified by a node number, which enables transparent IP address assignment. The IP address of the station consists of the network address of the master and the node number of the station.

The stations can communicate directly with one another: They can send messages to other stations during their transmission time without going through the master. While one station is transmitting, the other stations listen and recognize by means of the node number whether this telegram is addressed to them.