We've been aggregating data from smart devices in factories for 10 years. Ethernet is the dominate protocol, but only for non-time critical (non-deterministic) uses. The problem is always the protocol for information exchange (not talking about TCP/IP but at the app level), OPC tried to address it in a general way, XML gose a long way too, but none get rid of custom programming. Until there is a generally accepted way of communicating INFORMATION (not just the bits and bytes) this will be a hard thing to get a grip on. Not to mention most plant managers couldn't give a fig about the technology, SHIP PRODUCT!