5-2 Connecting to the Host Using Controller Link 
Troubleshooting with LNK Indicator  
- Data Links Cannot Be Started 
The following table describes the LNK indicator and remedies when a data link cannot be 
started. 
Starting a data link depends on the Controller Link Interface Unit operating normally and par-
ticipating in the network. Refer to Troubleshooting with RUN, ERC, ERH, and INS Indicators 
earlier in this section and check operation before using the following table. 
 
Indicator 
LNK 
Probable cause 
Remedy 
Lit  Data link operating normally.   
Flashing  There is an error in the data link tables.  If ERH or ERR indicator is lit, reset 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. 
Create the data link tables for the startup 
node using the CX-Server. 
Not lit  Manually set data links are already operat-
ing on the same Network. 
Set data link tables for the local node. 
  Automatically set data links are already 
operating on the same Network. 
Stop the data links, review and set the 
parameters in the startup node's DM area, 
and then restart.  
The PT cannot be the startup node for 
automatic settings. Settings must be per-
formed at Controller Link Unit on the PLC.
 
- Node Cannot Participate in Data Links 
The following table describes the LNK indicator and remedies when a Node cannot partici-
pate in the data links. 
Data link participation in the network depends on the Controller Link Interface Unit operating 
normally and participating in the network. Refer to Troubleshooting with RUN, ERC, ERH, and 
INS Indicators earlier in this section and check operation before using the following table. 
 
Indicator 
LNK 
Probable cause 
Remedy 
Lit  Data Link operating normally.   
Flashing  When manual setting is used, there is an 
error in the data link table. 
Reset data link tables using the CX-
Server. 
Not lit  When manual setting is used, there are no 
Data Link Tables set for the local node. 
Set the data link tables for the local node. 
  When automatic setting is used, the setup 
node is not set to participate in the data 
links. 
Stop the data links, remake and set the 
parameters in the Startup node’s DM 
Area, and then restart the data links. 
Setting must be performed at PLC on the 
Controller Unit side, because the Control-
ler Link Interface Unit cannot be the 
startup node for automatic settings. For 
details, refer to the Controller Link Units 
Operation Manual. 
 
 
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