Local Network Table; Relay Network Table - Omron CJ2 CPU UNIT SOFTWARE User Manual

4 CPU Unit Initialization
Tables Comprising Routing Tables
Routing tables consist of the following two tables.

Local Network Table

Network addresses from 1 to 127 are set for the Network Communications Units (CPU Bus Units)
connected in the local PLC. The local network table is used by the CPU Unit to identify Network
Communications Units mounted to the local PLC and the corresponding communications networks if
more than one Network Communications Unit is mounted to the PLC.
This table shows which Network Communications Unit
connected in the local PLC must be passed through to
reach a specified network.
Local PLC
The local network table gives the unit number of the Network Communications Unit connected in the
local PLC and the corresponding address of the FINS network connected to that Unit for FINS commu-
nications.

Relay Network Table

A relay network table is set to perform FINS communications across network layers. The relay network
table tells how to relay communications until the message reaches the final destination. The table gives
the network address and node address of the first relay point (i.e. first point to reach) on the route to a
destination network (final network) to which the local PLC is not connected.
The destination network is reached by progressing through the relay points.
Relay Network Table
Destination network
address
(final destination)
a
Message addressed to network
"a" is received.
4-12
Unit number: A
Unit number: B
Unit number: C
Network c
Network b
Network a
Relay
Node
Network
address
address
n
b
Node n
Node m
Network b
Local Network Table
Network address
a
b
c
Relay Network Table
Destination network
address
Network
(final destination)
address
b a
Message addressed to
network "b" is received.
Network a
Unit number
A
B
C
Relay
Node
address
m
CJ2 CPU Unit Software User's Manual