The FINS communication service was developed by OMRON so that PLCs and computers on different networks can communicate with each other in a consistent way. Among compatible network types there are Ethernet, Host Link, Controller Link, SYSMAC LINK, SYSMAC WAY, and Toolbus. The FINS communication service allows communication among nodes with up to 3 (three) depth layers. Direct links between a computer and a PLC through a Server link are not considered as network layers.

The diagram on the next figure shows a FINS network composed by interconnected SYSMAC LINK and Controller Link networks, and it serves as an example for the following discussion. The FINS communication service allows communication between any pair of devices on the diagram. PLC 1 (one) works as server's Host Link interface to network 1 (one). PLC 2 (two) works as a gateway between networks 1 (one) and 2 (two). In this example, the server computer sends a data request command, shown in red, to PLC 4 (four) via PLCs 1 (one) and 2 (two). The response is shown in blue. Initially, PLCs 4 (four) or 5 (five) could work as gateways to a third network layer, which could also be reached by the server computer.

FINS network diagram