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Troubleshooting Section 9-3
9-3 Troubleshooting
9-3-1 CPU Unit’s ERR/ALM Indicator Lit or Flashing
Use the following table to troubleshoot the network when the DeviceNet Unit
is mounted and the CPU Unit’s ERR/ALM indicator is lit or flashing.
Note Refer to the CS1 Series CPU Unit Operation Manual (W339) or the CJ Series
CPU Unit Operation Manual (W393) for more details on these errors.
9-3-2 Remote I/O Communications Disabled
Use the following table to troubleshoot the network when remote I/O data
communications won’t start. (The I/O Data Communications Flag remains
OFF in Master Status 1.)
Error Probable cause
An I/O verification error occurred. • Make sure that the Unit is connected properly.
• Check the I/O table with the I/O Table Verification operation and correct it
if necessary. After correcting it, perform the I/O Table Create operation.
A CPU Bus Unit setting error occurred. • The CPU Bus Unit model registered in the I/O table does not match the
model of CPU Bus Unit actually mounted. Check the I/O table with the I/O
Table Verification operation and correct it if necessary.
• After correcting the I/O table, perform the I/O Table Create operation.
A CPU Bus error occurred. • Make sure that the Unit is connected properly.
• Restart the Unit. Replace the Unit if it doesn’t restart.
An I/O Bus error occurred. • Make sure that the Unit is connected properly.
• Restart the Unit. Replace the Unit if it doesn’t restart.
Error Probable cause
All of the DeviceNet Unit’s indicators are OFF. • Check whether power is being supplied to the PC.
• Check whether the DeviceNet Unit is mounted in the Backplane cor-
rectly.
• When a watchdog timer (WDT) error has occurred in the PC, follow
the procedures described in the PC’s manual to correct the problem.
• All of a CS1W-DRM21 or CJ1W-DRM21 Unit’s indicators will be OFF
when a CPU Bus Unit error has occurred. Check for a CPU Bus Unit
error.
• Restart the Unit. Replace the Unit if it doesn’t restart.
The DeviceNet Unit’s MS indicator is ON and
green, but the NS indicator remains OFF.
(The NS indicator normally goes ON about 2 s
after the MS indicator.)
• If the DeviceNet Unit’s 7-segment display is displaying an error code,
refer to the tables in 9-1 Troubleshooting with the DeviceNet Unit In-
dicators.
• Make sure that the master’s unit number setting is correct.
• Make sure that the unit number is not duplicated on another Special
Unit.
• Check the I/O table with the I/O Table Verification operation and cor-
rect it if necessary. After correcting it, perform the I/O Table Create
operation.
Restart the Unit. Replace the Unit if it doesn’t restart.