Mitsubishi Electric MELSEC-A Series Manual page 43

2
REPLACEMENT OF MELSECNET (II) AND /B (PLC TO PLC NETWORK)
(3) Comparison between MELSECNET/B module (twisted pair) and MELSECNET/H module
(optical loop/coaxial bus)
Item
Max. 2048 points and max. number of I/O
X/Y
points of CPU module on master station
Maximum • (MELSECNET mode) 1024 points
number of • (MELSECNET II mode),
B
link points (MELSECNET II composite mode) 4096
per network points
• (MELSECNET mode) 1024 points
• (MELSECNET II mode),
W
(MELSECNET II composite mode) 4096
points
• (MELSECNET mode) 1024 bytes
Maximum number • (MELSECNET II mode),
of link points per (MELSECNET II composite mode)
station Link parameter first half: 1024 bytes
Link parameter second half: 1024 bytes
Communication
speed
Number of stations
connected in one
network
Applicable cable
Overall distance
Distance between
stations
Maximum number
of networks
Communication
method
Transmission
method
Specifications
MELSECNET/B module
Twisted pair
125kbps/250kbps/500kbps/1Mbps
32 stations (master station: 1,
local station + remote I/O station: 31)
Shielded twisted pair cable
125kbps: 1200m
250kbps: 600m
500kbps: 400m
1Mbps: 200m
125kbps: 1200m
250kbps: 600m
500kbps: 400m
1Mbps: 200m
-
Half duplex bit serial method
Single bus
: Compatible,
MELSECNET/H module
Optical loop Coaxial bus
(QJ71LP21-25) (QJ71BR11)
(MELSECNET/10 mode),
(MELSECNET/H mode),
(MELSECNET/H extended mode) 8192
points
• (MELSECNET/10 mode) 8192 points
• (MELSECNET/H mode),
(MELSECNET/H extended mode)
16384 points
• (MELSECNET/10 mode) 8192 points
• (MELSECNET/H mode),
(MELSECNET/H extended mode)
16384 points
• (MELSECNET/10 mode),
(MELSECNET/H mode)
{(LY + LB)  8 + (2 × LW)}
2000 bytes
• (MELSECNET/H extended mode)
{(LY + LB)  8 + (2 × LW)}
35840
bytes
25Mbps/10Mbps -
- 10Mbps
64 stations (control
station: 1 -
normal station: 63)
32 stations (control
- station: 1
normal station: 31)
SI optical cable
H-PCF optical cable
Broad-band H-PCF -
optical cable
QSI optical cable
3C-2V
-
5C-2V
30km -
3C-2V: 300m
-
5C-2V: 500m
Refer to Section
-
2.2.2.
3C-2V: 300m
-
5C-2V: 500m
239
Token bus method
Duplex loop -
- Single bus
: Partial change required, × : Incompatible
Compat- Precautions for
ibility replacement
When the number of bytes
exceeds 2000, mount two
modules having the same
network No., or set all
modules on the network in
the MELSECNET/H
extended mode.
Set the remote I/O network
to a separate network.
Set the remote I/O network
to a separate network.
A new optical cable has to
be installed.
A new coaxial cable has to
be installed.
Either use an A6BR10/
A6BR10-DC type repeater
unit, or configure a
separate network.
When 1200 m is required,
use GI optical cables for all
optical cables, and use
QJ71LP21G as the
module.
Either use an A6BR10/
A6BR10-DC type repeater
unit, or configure a
separate network.
New MELSECNET/H
parameter (mandatory)
Nothing to be noted though
the communication method
differs.
Nothing to be noted though
the transmission method
differs.
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