
348
Using the LED Indicators and Display for Troubleshooting Section 14-2
Lit red Not lit H3 EtherNet/IP 
Unit or built-in 
EtherNet/IP 
port faulty
--- Operation stops. --- Replace the Ether-
Net/IP Unit or (for a 
built-in EtherNet/IP 
port) the CPU Unit 
if the error recurs 
when the Unit is 
restarted.
Flashing 
red Not lit H4 Node address 
setting error The node 
address set on 
the switches is 
invalid (00 or 
FF.)
Operation stops. --- Set the node 
address correctly 
and restart the Eth-
erNet/IP Unit or 
built-in EtherNet/IP 
port.
Flashing 
red Not lit H6 CPU Unit 
faulty --- Records the error in 
the error log (time/
date all zeroes).
Operation stops.
000F Replace the CPU 
Unit if the error 
recurs when the 
CPU Unit is 
restarted.
Flashing 
red Not lit H7 I/O table not 
registered The CPU Unit’s 
I/O table is not 
registered.
Operation stops. 0006 Create the I/O 
table.
Flashing 
red --- H8 Simple backup 
function 
restore error
The simple 
backup func-
tion’s data resto-
ration failed.
The settings of the 
EtherNet/IP Unit or 
built-in EtherNet/IP 
port are all cleared, 
unless the backup file 
does not exist, a 
Memory Card is not 
mounted, or the PLC 
model does not 
match.
--- Perform the simple 
backup operation 
again. If the error 
recurs, replace the 
Memory Card, or 
EtherNet/IP Unit, 
or (for a built-in 
EtherNet/IP port) 
the CPU Unit.
Flashing 
red --- H9 I/O bus error An error 
occurred while 
exchanging data 
with the CPU 
Unit.
•If the Unit is the orig-
inator of the tag data 
link connection, it 
stops communica-
tions.
•If the Unit is the tar-
get of the tag data 
link connection and 
the PLC status is 
included in the com-
munications data, 
the corresponding 
Target Node PLC 
Error Flag will be 
turned ON.
000E Check and correct 
the CPU Unit’s 
operating environ-
ment.
Indicator Error Cause Unit operation (Flag 
status) Error 
log
(hex)
Countermeasure
MS NS 7-segment