Mitsubishi Electric RD77GF8 User Manual page 130

Check item
When the Ethernet device has two or more Ethernet ports, have
different default gateway settings been configured for each Ethernet
port?
Is the switching hub used operating normally?
Has any device on the line, such as an Ethernet device, Ethernet-
equipped module, Ethernet adapter module, and switching hub,
been replaced? (This applies only when the device has been
replaced by the one having the same IP address.)
*1 When the device has been reconnected to the switching hub, or the switching hub has been replaced, it may take some time to read the
MAC address. If so, retry communication from the Ethernet device again after a while or power on the switching hub again.
*2 A device on Ethernet has a table of IP addresses and their corresponding MAC address, called "ARP cache". When a device on the line
is replaced by the one having the same IP address, the MAC address in the ARP cache is different from that of the replaced device;
therefore, communications may not be normally performed. The "ARP cache" is updated by resetting the device or after a while. The
time varies depending on the device.
If the above actions do not solve the problem, perform the following tests to check for an error.
• Cable test (Page 116 Cable Test)
4 TROUBLESHOOTING
128
4.4 Troubleshooting by Symptom
Action
• Set the same IP address in the default gateway of each Ethernet port.
• Set the communication route on the Ethernet device side using the route command so
that communications using the IP packet transfer function can be transmitted to the
Ethernet device through the module connected to the Ethernet device. (This applies
only to Ethernet devices that have the route command, such as Microsoft

Windows .)
When the gateway setting is completed, execute the Ping command from the Ethernet
device to check whether communications can be performed.
• If an error has occurred in the switching hub, eliminate the error cause.
• If communications cannot be performed although no error has occurred in the
switching hub, replace the switching hub.
*2
Reset the device on the line.

*1