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*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 communications 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 on the master/local module to check for an
error.
• Hardware test (
• Self-loopback test (
• Cable test (
Is the antivirus software on the Ethernet device blocking the
communications?
Check and correct the antivirus software settings on the Ethernet device.
• Is the security setting level of the antivirus software low?
• Is a response to the Ping command (ICMP echo request) enabled in
the firewall settings?
When the Ethernet device has two or more Ethernet ports, have
different default gateway settings been configured for each
Ethernet port?
• 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.
Is the switching hub normal?
• If an error has occurred in the switching hub, remove the error.
• If communications cannot be performed although no error has
occurred in the switching hub, replace the switching hub.
*1
Has any device on the line, such as an Ethernet device, CPU
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 (This applies only when the device has been
replaced by the one having the same IP address.)
Reset the device on the line.
*2
Check item
Action
Ex.