Mitsubishi Electric MELSEC-A Series Manual page 117

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