Replacement Precautions - Mitsubishi Electric MELSEC-A Series Manual

2
REPLACEMENT OF MELSECNET (II) AND /B (PLC TO PLC NETWORK)

2.7 Replacement Precautions

The following shows the replacement precautions when replacing MELSECNET (II) with MELSECNET/
H.
(1) Cables
For details on precautions for optical cables and coaxial cables, refer to Section 2.2.2 Cable
performance comparisons.
(2) System configuration
(a) System configuration using local stations and remote I/O stations in MELSECNET mode
and MELSECNET II mode
MELSECNET/H system, which is a composite system comprising local stations and remote stations,
provides high-performance functions by making a separation between local stations and remote
stations. It therefore cannot be configured by a mixture of local stations and remote stations. For this
reason, in a MELSECNET (II) system, when replacing a system, which comprises a mixture of local
stations and remote I/O stations connected to a single master station, with a MELSEC/H system, the
following system configuration is necessary. Normal stations are connected to a single control
station, and remote I/O stations are controlled by an additional remote master station (the control
station in a remote I/O system is defined as the "remote master station"). The following shows a
system configuration example.
For a parameter change example, refer to Section 3.5.2.
MELSECNET ( II ) (optical)
Optical loop
M
L1
L2
(b) MELSECNET (II) system comprising 65 connected modules
The maximum number of stations on the MELSECNET/H system is 64 (one control station, 63
normal stations).
The maximum number of stations on the MELSECNET (II) system is 65 (one master station, 64 local
stations + remote I/O stations). For this reason, when the maximum number of 65 MELSECNET/H
modules are connected, measures (e.g. division into two networks of 64 modules or less having a
different network No.) are required.
System configuration using local and remote stations (optical)
MELSECNET/H (optical)
Optical loop
1M
1N 1 Network
S
2M
1
R3
1N 2
S
Remarks (proposed measure)
• The control station of network No.1
configures a PLC to PLC network that
controls normal station 1 and normal
4/
P
Network 2R3
station 2.
R
2
• The other network module becomes the
remote master station, and the remote I/O
network system of No.2 is configured.
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