Protocols
Although the use of Ethernet standardizes the physical transport of data in an industrial setting, multiple different incompatible protocols are used and encapsulated into Ethernet data frames. Intermediate network hardware such as routers and switches may be indifferent to the data protocol encapsulated in each Ethernet frame, but source and consumer devices must use the same protocol to allow communication to take place. Some standards, such as Modbus, have been adapted from their original versions and converted to a form that can be transmitted over an Ethernet network. For example, Profibus has been developed into an Ethernet compatible standard, PROFINET. Other protocols, such as EtherNet/IP have been developed only for the Ethernet transport layer. Industrial network protocols can be encapusulated inside TCP data frames, further standardizing their handling, but requiring a TCP-compatible protocol stack to be present at each end of a data connection.
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