Method for data communication with reduced overhead in a real-time capable Ethernet data network
In order that in a real-time capable Ethernet data network protocol the cycle time of the transmission cycles in a real-time capable Ethernet data network can be shortened, according to the invention a plurality of slaves (S 1 , S 2 , S 3 , S 4 , S 5 ) is combined into a sum frame group (SG) and a slave (S 2 , S 4 ) of the sum frame group (SG) is specified as collector node (SK) and all other slaves (S 1 , S 2 , S 3 , S 4 , S 5 ) of the sum frame group (SK) transmit their data in each case with a collective data packet (DPS 1 , DPS 2 , DPS 3 , DPS 4 , DPS 5 ) to the collector node (SK) transmit, the collector node (SK) inserts the data of the other slaves (S 1 , S 2 , S 3 , S 4 , S 5 ) of the sum frame group (SG) into a sum frame data packet (DPSR) and the collector node (SK) transmits the sum frame data packet (DPSR) to the master (M).
1. A method for data communication in a real-time capable Ethernet data network, in which at least one master is connected via an Ethernet data network to a plurality of slaves and data in the form of data packets are transmitted between the master and the slaves, the method comprising:
combining at least some of the plurality of slaves into a sum frame group and a slave of the sum frame group is specified as a collector node and all other slaves of the sum frame group transmit their data in each case with a collective data packet to the collector node,
wherein the collector node inserts the data of the other slaves of the sum frame group into a sum frame data packet and the collector node transmits the sum frame data packet to the master.
2. The method according to claim 1 , wherein a slave of the sum frame group which is furthest away from the master on the data network is selected as the collector node.
3. The method according to claim 1 , wherein a slave of the sum frame group which is arranged nearest to the master on the data network is selected as the collector node.
4. The method according to claim 1 , wherein a slave in a middle of the sum frame group is selected as the collector node.
5. The method according to claim 1 , wherein for each slave of the sum frame group transmitting to the collector node a bit which indicates whether the data have been validly received from the collector node is contained in the sum frame data packet.