We are designing a point-to-point ring Ethernet network for a data acquisition system. Due to physical system constraints, star/mesh networks are out of the question.
For data transmission to a host, we are using point-to-point links to daisy chain the boards with packets hopping from one to the next towards the host.
I've read up on transmit and receive Ethernet packets using the MAC but, along with the Ethernet control packets (pause etc).
However I'm unclear on how to send a robust event trigger to all 12 nodes. My previous experience was with USB and a single device that needed a trigger end point. However sending a trigger to multiple Ethernet addresses at the same time is unclear.
As the distances between nodes mean a trigger would arrive at the node closest to the host first. I was thinking of transmitting frames that contain a 'please trigger flag' and a wait duration to each node. This pause would be slightly different for each node allowing acquisition to be synchronised.
What are people's thoughts? We are using Xilinx Spartan 6 FPGAs at each node with the MAC IP-Cores, probably 10-100Mb/s Ethernet and a decent amount of buffer memory per node.
Thanks. Ed
How about using UDP sending on broadcast address? There is also another similar question answered