Mitsubishi Electric Melsec A Series - Page 117

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REPLACEMENT OF MELSECNET (II) AND /B (REMOTE I/O NETWORK)
3
(2) Comparison between MELSECNET (II) module (coaxial loop) and MELSECNET/H
module (coaxial bus)
: Compatible, : Partial change required, × : Incompatible
Item
Specifications
Compat-
ibility
Precautions for replacement
MELSECNET (II) module MELSECNET/H module
Coaxial loop Coaxial bus (QJ71BR11, QJ72BR15)
Maximum
number of
link points
per
network
X/Y
Max. 2048 points and max. number of
I/O points of CPU module on master
station
8192 points
B-
16384 points
(Remote master station  remote I/O
station: 8192 points, remote I/O station
 remote master station: 8192 points)
W
• (MELSECNET mode) 1024 points
• (MELSECNET II composite mode)
4096 points
16384 points
(Remote master station  remote I/O
station: 8192 points, remote I/O station
 remote master station: 8192 points)
Maximum
number of
link points
per
station
Master
station
• (MELSECNET mode) 1024 bytes
• (MELSECNET II composite mode)
link parameter first half: 1024 bytes
Remote master station  remote I/O
station
{(LY + LB)  8 + (2 × LW)} 1600 bytes
Remote
I/O
station
512 bytes
Remote I/O station  remote master
station
{(LX + LB)  8 + (2 × LW)} 1600 bytes
Maximum number of
I/O points per station
512 points 4096 points
Communication
speed
1.25 Mbps 10 Mbps
Number of
stations
connected in one
network
65 stations (Master station: 1, local
station + remote I/O station: 64)
33 stations (Remote master station: 1,
remote I/O station: 32)
• Set the PLC to PLC network
to a separate network.
• For stations over 33, build a
separate network.
Applicable cable
3C-2V
5C-2V
When using existing cables,
the overall distance and
distance between stations
becomes shorter.
Overall distance
3C-2V: 10km
5C-2V: 10km
3C-2V: 300m
5C-2V: 500m
Either use an A6BR10/
A6BR10-DC type repeater
unit, or configure a separate
network.
Distance between
stations
3C-2V: 500m
5C-2V: 500m
3C-2V: 300m
5C-2V: 500m
When using the 3C-2V, use
the A6BR10/A6BR10-DC type
repeater unit.
Maximum number of
networks
-239
New MELSECNET/H
parameter (mandatory)
Communication
method
Half duplex bit serial method Token ring method
Nothing to be noted though the
communication method differs.
Transmission
method
Duplex loop Single bus
Nothing to be noted though the
transmission method differs.
Modulation method
(Encoding method)
(Modulation method) CMI method (Encoding method) Manchester code
Nothing to be noted though the
modulation method differs.
Transmission
format
HDLC standards (frame format)
Error control
system
CRC (X
16
+X
12
+X
5
+1) and retry by a time over
RAS function
• Loop-back function due to error
detection or broken cable
• Diagnostic function for checking
local link lines
Diagnostic function for checking local
link lines
The loopback function cannot
be used on a coaxial bus
system.
To use the loopback function,
using an optical loop system is
recommended.
Number of occupied
I/O points
(Master station)
CPU integrated type: 0 point
Standalone:32 points per slot (I/O
assignment: special 32 points)
(Master station)
32 points per slot (I/O assignment: intelli.
32 points)
When the master station is
replaced from a CPU
integrated type, one new slot
(32 points) is required.