MODBUS Protocol Confusion


Thread Starter


I have customers specify different communication protocols they want and a lot of times they use different terminology but maybe are talking about the same thing. My main question is:

Is there is a difference between Modbus TCP, Modbus TCP/IP, Ethernet TCP/IP, TCP/IP?

Curt Wuollet

Yes. The first two may very well be the same thing, probably, almost certainly as TCP is a layer over IP.

The third is TCP specified to be running over Ethernet without any indication that Modbus is involved and the fourth is simply the TCP/IP method for reliable packet transmission with no mention of physical layer or that Modbus is involved. Modbus TCP is simply embedding a Modbus payload in a TCP packet. with a few accommodations. But neither Ethernet or TCP/IP implies Modbus TCP.