|
<< Click to Display Table of Contents >>
Routing Tables |
With multi-level networks, every additional information must be programmed in the devices, 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 device'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 PLC 1 device
Network Number |
Unit |
1 |
1 (one) |
As the PLC 1 device is only connected to the SYSMAC LINK network, it has only one entry in its local routing table.
Remote PLC 1 device
Network Number |
Relay Network |
Relay Node |
2 |
1 (one) |
2 (two) |
Network 2 (two) is a remote network for the PLC 1 device. To send a message to a node on network 2 (two), this device 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, the PLC 2 device, is the node number 2 (two). Therefore, the relay node for the PLC 1 device is equal to 2 (two).
Local PLC 2 device
Network Number |
Unit |
1 |
2 (two) |
2 |
1 (one) |
There are two local networks for the PLC 2 device. 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 PLC 2 device could be named as "node 10", for example, as they are on different networks.
Local PLC 3 device
Network Number |
Unit |
1 |
1 (one) |
The local routing table for the PLC 3 device contains only one entry, as this device is only connected to network 1 (one).
Remote PLC 3 device
Remote Network Number |
Relay Network |
Relay Node |
2 |
1 (one) |
2 (two) |
Network 2 (two) is a remote network for the PLC 3 device. As in the PLC 1 device, the relay network is 1 (one), and the relay node is 2 (two, the SLK module of the PLC 2 device's gateway).
Routing tables for PLC 4 and PLC 5 devices must look like the following tables. In this example, they are the same because Controller Link modules in both devices are number 1 (one) units. Users must assign node numbers to these modules that are unique in network 2 (two).
Local PLC 4 and PLC 5 devices
Network Number |
Unit |
2 |
1 (one) |
Remote PLC 4 and PLC 5 devices
Network Number |
Relay Network |
Relay Node |
1 |
2 (two) |
1 (one) |