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Troubleshooting Section 9-3
9-3-4 Communications Error Operation Settings
Use the following table to correct problems with the DIP switch setting for con-
tinuing/stopping communications for errors.
9-3-5 Scan List Problems
Use the following table to troubleshoot scan list problems.
Error Probable cause
Communications are stopped even though
there is no communications error.
When pin 3 on the DIP switch is ON, communications will be stopped if a
communications error, transmission timeout, or network power supply error
occurs.
While communications are stopped, the 7-segment displays will alternately
display error code A0 and the error code of the communications error that
caused the stoppage.
After a network power supply error or transmission timeout is corrected, the
indicators will show just the communications stoppage code (A0).
Communications are stopped by the DIP
switch setting, but don’t resume after tog-
gling the Clear Communications Error Stop-
page Bit.
• When communications can’t be restarted with slaves that were communi-
cating normally before the stoppage, stop the communications again.
Check that the slave has started up and perform the “clear communica-
tions error stoppage” operation.
• It may be necessary to perform the operation twice if the network contains
another company’s slave that take a long time to join the network.
Error Probable cause
A scan list couldn’t be created by the “cre-
ate scan list” operation.
A scan list couldn’t be cleared by the “clear
scan list” operation.
Neither the create scan list nor clear scan list operations can be performed
until the I/O Data Communications flag goes ON. (The I/O Data Communi-
cations flag will be OFF for a short time after the power is first turned ON
and after the scan list clear operation is executed.)
Make sure that the I/O Data Communications flag is ON before attempting
to execute the create scan list or clear scan list operations.
The “create scan list” or “clear scan list”
operation was executed, but the master’s 7-
segment displays still display “- -”.
(The “- -” display usually lasts for 1 s after
the “create scan list” operation or 0.1 s after
the “clear scan list” operation.)
Restart the DeviceNet Unit, execute the clear scan list operation, and then
the create scan list operation if necessary.
Replace the DeviceNet Unit if this doesn’t correct the problem.