Mitsubishi Electric MELSEC-A Series Manual page 42

2
REPLACEMENT OF MELSECNET (II) AND /B (PLC TO PLC NETWORK)
(2) Comparison between MELSECNET (II) module (coaxial loop) and MELSECNET/H
module (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)
per network 4096 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 First half: 1024 bytes
Second half: 1024 bytes
Communication
speed
Number of stations
connected in one
local station + remote I/O station: 64)
network
Applicable cable
Overall distance
Distance between
stations
Maximum number
of networks
Communication
method
Transmission
method
Modulation
method (Encoding
method)
Transmission
format
Error control
system
• Loop-back function due to error
detection or broken cable
RAS function
• Diagnostic function for checking local
link lines
Number of CPU integrated type: 0 point,
occupied I/O Standalone:32 points per slot (I/O
points assignment: special 32 points)
2
- 5
Specifications
MELSECNET ( II ) module
Coaxial loop
1.25Mbps
65 stations (master station: 1,
3C-2V
5C-2V
3C-2V: 10km
5C-2V: 10km
3C-2V: 500m
5C-2V: 500m
-
Half duplex bit serial method
Duplex loop
(Modulation method) CMI method
HDLC standards (frame format)
16 12 5
CRC(X +X +X +1) and retry by a time over
: Compatible,
MELSECNET/H module
Coaxial bus (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
10Mbps
32 stations (control station: 1, normal
station: 31)
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
32 points per slot (I/O assignment: intelli.
32 points)
: 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.
• For the 33th station,
configure 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 replacing from a CPU
integrated type, an additional
slot (32 points) is required.