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Routing Tables |
With multi-level networks, every additional information must be programmed in the PLCs so that they can send messages to other nodes in the system. This is accomplished by using FINS routing tables. FINS routing tables are Local and Remote. Local routing tables associate a network number with one of the communication modules (SIOU, or Special Input or Output Units) installed in the PLC's rack. Remote routing tables give directions on how to reach one of the next network levels. The routing tables for the previous example are described next.
Local PLC1
Network Number |
Unit |
1 |
1 (one) |
As PLC1 is only connected to the SYSMAC LINK network, it has only one entry in its local routing table.
Remote PLC1
Network Number |
Relay Network |
Relay Node |
2 |
1 (one) |
2 (two) |
Network 2 (two) is a remote network for PLC1. To send a message to a node on network 2 (two), PLC1 must send that message to a relay node, that is, the gateway on one of its local networks. This local network is called a relay network, and it must be network 1 (one), in this case. The SYSMAC LINK module in the gateway, PLC2, is the node number 2 (two). Therefore, the relay node for PLC1 is 2 (two).
Local PLC2
Network Number |
Unit |
|---|---|
1 |
2 (two) |
2 |
1 (one) |
There are two local networks for PLC2. The SYSMACK LINK and Controller Link network numbers are arbitrarily assigned as unit numbers 2 (two) and 1 (one), respectively. The SYSMAC LINK and Controller Link modules are assigned as unit numbers 2 (two) and 1 (one), respectively. The network node number of each one of these modules is configured by the user, and it must be unique within its associated network. Both communication modules in the PLC2 could be named as "node 10", for example, as they are on different networks.
Local PLC3
Network Number |
Unit |
1 |
1 (one) |
The local routing table for PLC3 contains only one entry, as this device is only connected to network 1 (one).
Remote PLC3
Remote Network Number |
Relay Network |
Relay Node |
2 |
1 (one) |
2 (two) |
Network 2 (two) is a remote network for PLC3. As in PLC1, the relay network is 1 (one), and the relay node is 2 (two, the SLK module of PLC2 device's gateway).
Routing tables for PLCs 4 (four) and 5 (five) must look like the following tables. In this example, they are the same because Controller Link modules in both PLCs are number 1 (one) units. Users must assign node numbers to these modules that are unique in network 2 (two).
Local PLCs 4 (four) and 5 (five)
Network Number |
Unit |
2 |
1 (one) |
Remote PLCs 4 (four) and 5 (five)
Network Number |
Relay Network |
Relay Node |
1 |
2 (two) |
1 (one) |