Controller Link Units Operation Manual
279
Troubleshooting Using Indicators Section 9-1
Troubleshooting with LNK and M/A Indicators
Data Link Cannot be 
Started
The following table describes the LNK and M/A indicators at the startup node
and their use in troubleshooting when a data link cannot be started.
Starting a data link depends on the Controller Link Unit operating normally
and participating in the Network. Refer to Troubleshooting with RUN, ERC,
ERH and INS Indicators earlier in this section and check Unit operation before
using the following table. 
Indicators Probable cause Probable remedy
LNK M/A
Lit --- Data link operating normally. ---
Flashing --- There is an error in the data 
link tables.
When the ERH indicator is 
flashing, remake and set the 
data link tables.
When manual setting is used, 
either data link tables have not 
been created for the startup 
node or there is an error in the 
data link tables.
Refer to 5-2-2 Manual Setting 
and set data link tables for the 
startup node.
When automatic setting is 
used, either the data link 
parameters for the startup 
node have not been set or 
there is an error in the data link 
tables.
Refer to 5-2-4 Automatic Set-
ting and set the automatic 
parameters for starting the 
data links.
Automatic setting is used with 
1:N allocations, but the device 
does not support this function.
Use a Controller Link Unit that 
supports automatic data link 
creation with 1:N allocations. 
Refer to Automatic Setting on 
page 129 for details.
When a number exceeding 
12,000 was set for the data 
link send and receive words or 
the same memory area was 
set for Area 1 and Area 2 
using a CS/CJ-series Control-
ler Link Unit with unit version 
1.2 or later that was then 
replaced with a CS/CJ-series 
pre-Ver. 1.2 Controller Link 
Unit.
The number of data link send 
and receive words cannot 
exceed 12,000 and the same 
memory area cannot be set for 
Area 1 and Area 2 when using 
a CS/CJ-series pre-Ver. 1.2 
Controller Link Unit. Either use 
a CS/CJ-series Controller Link 
Unit with unit version 1.2 or 
later or reset the data link 
tables. 
Not lit Lit Manually set data links are 
already operating on the same 
Network.
Stop the manually set data 
links that are operating and 
restart the data links.
Not lit Not lit Automatically set data links 
are already operating on the 
same Network.
Stop the automatically set data 
links that are operating and 
restart the data links.
There is an error in the startup 
node PLC.
Refer to the PLC’s operation 
manual and correct the error. If 
the error reoccurs, replace the 
PLC.










