Panasonic FP7 Series Command Reference Manual page 1185

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Default gateway setting
● Setting may not be possible depending on the combination of IP address and default
gateway.
● Specify "000.000.000.000" when default gateway is not to be used.
● Setting is not possible in the following case.
(IP address AND netmask) ≠ (Default gateway address AND netmask)
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Judgment based on the combination of IP address and net mask
● The following combination is not possible.
● IP address AND (Inverse all bits of net mask: 1's complement) = 0
● IP address OR (net mask) = 255.255.255.255
● Only when the router IP address is other than 000.000.000.000, the above combination
judgment is performed for the routing setting.
*The combination above may occur when masks are set to omission using IPv4SET instruction.
Example) When the net mask is 255.255.0.0, set the IP address = 0.0.255.255 using IPv4SET.
The set values for IP address, net mask and default gateway are initialized when
communication process is performed using the combination above. Default values are as
follows.
IP address =192.168.1.5, Net mask = 255.255.255.0, Default gateway = 192.168.1.1
WUME-FP7CPUPGR-12
19.10 Ethernet Function: IP Addresses
19-25