The Modbus TCP protocol uses a Client/Server architecture for data exchange.
Modbus TCP explicit (non-cyclic) data exchanges are managed by the application.
Modbus TCP implicit (cyclic) data exchanges are managed by the Modbus TCP IOScanner. The Modbus TCP IOScanner is a service based on Ethernet that polls slave devices continuously to exchange data, status, and diagnostic information. This process monitors inputs and controls outputs of slave devices.
Clients are devices that initiate any data exchange with other devices on the network. This applies to both I/O communications and service messaging.
Servers are devices that address any data requests generated by a Client. This applies to both I/O communications and service messaging.
The communication between the Modbus TCP IOScanner and the slave device is accomplished using Modbus TCP channels.
