3-1 Routing Table Overview
3-1-1 Definition of Routing Tables
3-1 Routing Table Overview
3-1-1 Definition of Routing Tables
To transfer data between networks, it is necessary to create tables that specify the
paths from the local PLC's Communications Units (such as a Controller Link Unit) to
the networks in which the other PLCs are connected. These tables are called routing
tables.
Routing tables consist of the following two tables.
1) Local network table
2) Relay network table
Note: Routing tables are required in any of the following cases.
1. Required when communicating (using message communications or remote
programming/monitoring from the CX-Programmer) with a PLC in a network other than
the local network.
2. Required when two or more Communications Units are mounted to a single PLC (i.e.,
under a single CPU Unit). Routing tables are not required when just one
Communications Unit is installed in each PLC and those Communications Units are
connected in a single network.
3. Required when routing tables are set in two or more nodes in the same network.
Local Network Table
The local network table lists the unit number and network address of the
Communications Units mounted in each PLC in the local network. A local network
table is required to distinguish between network addresses when two or more
Communications Units are mounted in a single PLC.
When data is being transferred from the PLC to a destination network address, the
local network table indicates which Communications Unit can be used to send data to
the destination network address.
Unit number Local network address
Local Network Table
Unit number: Unit number of the Communications Unit
Local network address: Address of the network to which the Communications
Unit is connected
Network address 3
Network address 2
Network address 1
Unit number 00
Unit number 01
Unit number 02
Local Network Table
Unit number Local network address
00 1
01 2
02 3
The unit number is the number (0 to 15) set on the rotary switch on the front of each Communications Unit.
The network address is the address of the network (1 to 127) of the network to which the Unit belongs.
Set these values when creating the local network table in the routing tables.
3-2
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