In "Old Machines, New Data" (www.IndustrialNetworking.net/legacy), Dan Hebert didn't mention the only industrial Ethernet that makes connecting to legacy networks part of the specification: Profinet.

We have specs for proxies from Profinet to Profibus-DP, Profibus-PA, FF, DeviceNet, CANopen, and more.

To protect the users' investment in Profibus, Profinet uses an ingenious method to integrate the world’s most popular fieldbus: a proxy. Similar to a gateway in that it connects disparate protocols, it differs because the proxy is specified in the Profinet spec.

This technique worked so well for the largest installed fieldbus base, Profibus, that the No. 2 fieldbus, Interbus, decided to use Profinet instead of developing its own industrial Ethernet. The technique worked so well that the organization supporting Profinet also specified proxies for DeviceNet and many other legacy buses.

Carl Henning, Deputy Director,
PI North America,
www.us.profibus.com