Ip Address In Use Detection Function - Mitsubishi Electric QJ71E71-100 User Manual

14.6

IP Address in Use Detection Function

If different stations in the same network use the same IP address, the address in use can be detected. This prevents a
network from stopping due to incorrect IP address.
This function is available only in the QJ71E71-100 with the serial number (first five digits) of "12062" or later. When the
connected device with the same IP address does not support the IP address in use detection function, the error is not
detected.
The station that has been already
connected to the network continues
communications even if the station
with the same IP address is connected.
10.97.24.1 (Already in use)
(1) Checking the IP address already in use
The following two methods are available:
• Checking buffer memory areas
• Checking using the Ethernet diagnostics
(a) Checking buffer memory areas
Both the station already connected to the network and the station with the same IP address (station connected
to the network later), and the MAC addresses of the stations with the same IP address can be checked. The
destination IP address can be checked only in the station with the same IP address (station connected to the
network later).
Buffer memory area
Destination IP address (stored in the station with the same IP
address connected to the network later.)
The MAC address of the station that has
been already connected to the network
(stored in the station with the same IP
address connected to the network later).
IP address status
storage area
The MAC address of the station with the
same IP address connected to the network
later (stored in the station that has been
already connected to the network).
IP address: IP address:
10.97.24.2
MAC address: MAC address:
00 26 92 89 2E 89 00 26 92 45 16 CC
If a station and another station with the same
IP address exist on the same network, another
station cannot be connected to the network.
(The COM.ERR. LED turns on, and COM.ERR.
LED lit confirmation (X1C) turns on.)
The module
connected later
IP address:
10.97.24.3 10.97.24.1 (Already in use)
MAC address:
00 1A 4D 5D 5D D8
Buffer memory
address
234 (EA )
The third and fourth octets of the IP address
H
235 (EB )
The first and second octets of the IP address
H
21121 (5281 )
The fifth and sixth octets of the MAC address
H
21122 (5282 )
The third and fourth octets of the MAC address
H
21123 (5283 )
The first and second octets of the MAC address
H
21124 (5284 )
The fifth and sixth octets of the MAC address
H
21125 (5285 )
The third and fourth octets of the MAC address
H
21126 (5286 )
The first and second octets of the MAC address
H
CHAPTER 14 OTHER FUNCTIONS
This station cannot
be connected to
the network,
resulting in
an error.
IP address:
MAC address:
00 26 92 DE 26 90
Description
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