Modbus TCP is essentially Modbus RTU, however Modbus TCP is used over ethernet
This means that a Modbus TCP device installed in Europe can be addressed over the Internet from the USA from anywhere else in the world.
The Benefits of Modbus TCP
It is openly published and royalty-free
Relatively easy industrial network to deploy
It is Modbus RTU over ethernet so there is a very small learning curve when upgrading
It moves raw bits or words without placing many restrictions on vendors
It is support by many users so in all types of products
Easiest EtherNet based protocol to implement
Modbus TCP’s Connection-Orientation
In Modbus, data transactions are traditionally stateless, making them highly resistant to disruption from noise and yet requiring minimal recovery information to be maintained at either end.
Programming operations, on the other hand, expect a connection-oriented approach. This was achieved on the simpler variants by an exclusive ‘login’ token, and on the MODBUS Plus variant by explicit ‘Program Path’ capabilities which maintained a duplex association until explicitly broken down.
Modbus TCP handles both situations. A connection is easily recognized at the protocol level, and a single connection may carry multiple independent transactions.
In addition, TCP allows a very large number of concurrent connections, so in most cases it is the choice of the initiator whether to reconnect as required or re-use a long-lived connection.
