Definition - What does Modbus TCP/IP mean?
Modbus TCP/IP is a simple Modbus protocol running on Ethernet over a TCP interface. Modbus is an application protocol that assigns the ways of managing and passing data between various layers without being affected by the protocol used by the next immediate layer.
Modbus TCP/IP is also known as Modbus-TCP.
Techopedia explains Modbus TCP/IP
Modbus TCP/IP uses Transmission Control Protocol and Internet Protocol for the transmission of messages from Modbus between compatible devices over various systems. That is, Modbus TCP/IP uses a physical network (Ethernet), with a networking standard (TCP/IP), and itself offers a method of representing data (Modbus as the application protocol). A Modbus TCP/IP message is basically just a Modbus communication data message compressed in an Ethernet TCP/IP cover. TCP/IP is simply a transport layer protocol and does not change the way data is stored or interpreted inside the message.