Someone sent me a handout from a Rockwell lunch and learn session that compared Ethernet/IP and PROFINET. It is so wrong that it will take me some time to compose the corrections. But in the meantime, I was amused by the last line of this FUD piece, under “Notes (Other Competitors)”: “Modbus TCP: Primary pusher -> Schneider. Small data quantities, low node count per network, performance limited, non-real-time network.” Why was I amused? Because the “analysis” is so wrong? No, it’s pretty accurate except maybe the low node count comment. There is no theoretical limit to the number of IO nodes Modbus TCP supports… although old, serial Modbus is limited to 99. No, I was amused because Rockwell and Schneider (and Modbus IDA and ODVA) are now supposed to be friends. See my report from Hanover Fair on the announcement of their agreement: “Hanover Fair – Day 2”. With friends like these…
*What is FUD? See my blog post on “Pegging the FUD meter”.