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MELSEC-Q
3 WHEN COMMUNICATING WITH MELSECNET/H, MELSECNET/10
RELAY
(2) IP address computation system
(a) Overview of the IP address computation system
During calculation, the IP address of the partner station is obtained from the
calculation equation below according to the Network No. and station
number, and the UDP port number predefined for the Ethernet module
system is used as the UDP port number of the destination.
For more information about the net mask pattern for MELSECNET/H,
MELSECNET/10, see Section 3.3.2.
IP address of the
partner station
Logical
product
Logical
sum
IP address of
the local station
Net mask pattern for
MELSECNET/H,
MELSECNET/10 routing
Network number
and station number
of the destination
=
(b) Conversion processing of the IP address computation system
1) When a communication request message (command frame) to access
other station is received, the IP address is calculated from the Network
No. and station number of the destination in the communication request
message, and the communication request message is sent to the next
station.
1 The Network No. and station number of the destination in the
communication request message are stored in the Ethernet module.
2) The response message (response) for the communication request
message is returned based on the return IP address and the stored data
above.
(c) IP address computation example
The logical sum is calculated differently depending on the class of the local
station IP address. An IP address is calculated as follows.
(For class A)
• When the local station IP Address is 79238102
H
• When the MELSECNET/H, MELSECNET/10 Routing Net Mask
Pattern is FF000000
H
• When the destination Network No. is 03
H
, and the station number is
05
H
Local station IP Address
Net Mask Pattern
Logical product
Logical product value
Network No. and station No.
Logical sum
Partner station IP Address
7
9
.
2
3
.
8
1
.
0
2
F
F
.
0
0
.
0
0
.
0
0
7
9
.
0
0
.
0
0
.
0
0
0
3
.
0
5
7
9
.
0
0
.
0
3
.
0
5
