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INTRODUCTION
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(c) 2-tier system 3: System configuration example using local stations/remote I/O stations
*1 As the transmission speed of MELSECNET/H is faster than MELSECNET(II), and as the transmission method is different, 
the distance between stations and overall distance become shorter.
MELSECNET( II ) MELSECNET/H System configuration precautions
Coaxial loop
Coaxial bus
1) Distance between stations: If this value 
exceed the Q series specification values 
when re-using the MELSECNET(II) 
system cables, 3C-2V has to be changed 
to 5C-2V.
*1
2) Overall distance: If this value exceeds the 
Q series specification value when 
MELSECNET(II) system cables are re-
used, measures (e.g. adding a repeater 
unit) are required.
*1
3) CPU: When replacing an integrated type 
CPU, one new slot (32 points) is required.
4) Duplex loop: When the transmission path 
has to be duplexed, changes to an optical 
loop system, etc. are required.
5) Composite system: As a mixture of a PLC 
to PLC network and a remote I/O network 
is not allowed on the Q series, the 
network has to be divided into two 
networks having different network Nos. 
For this reason, a separate network 
module for the remote master station is 
required.
6) New installation: A separate coaxial cable 
is required for the remote I/O stations.
1NS1 2R31NS2
Network 1
1M
P4/2MR
Network 2