EthernetIP driver or spec has no internal limits on communications across subnets as long as those subnets are routable, correct? Does anyone know of a device or documentation that would assist in this sort of network topology. We have a server with LV EthernetIP code on one subnet. PLC's will be on another subnet. Thanks for reading.
EtherNet/IP communication uses standard networking protocols including: TCP, UDP unicast, and UDP multicast. All three of these protocols can run across multiple subnets assuming the network is configured to route the traffic appropriately. TCP is mostly used for explicit messaging while the UDP is mostly used for I/O communication. The multicast UDP is likely the one that needs some care by your network administrator to ensure that it works across multiple subnets. Typically this can be configured to work automatically via IGMP snooping or by manully configuring certain multicast groups to be forwarded between subnets by your routers. You (or your network administrator) should probably read this whitepaper published by the ODVA: http://www.odva.org/Portals/0/Library/Publications_Numbered/PUB00035R0_Infrastructure_Guide.pdf