Omron CJ Series Operation Manual page 244

7 Troubleshooting
Event name Communications Error
Meaning A Slave Unit was disconnected from the network.
Source PLC Function Module
Error attributes Level
Effects User program
System-defined Variable
variables
None
Cause and Assumed cause
correction
Cable lengths (trunk line and branch
lines) are unsuitable.
A cable is disconnected or loose.
A terminating resistance is not con-
nected. Or, the terminating resistance
is somewhere other than the end of
the trunk line.
Noise
The Slave Unit does not respond to
communications from the Master Unit
because the Slave Unit is faulty, the
line is disconnected, or the communi-
cations power supply is interrupted.
Attached None
information
Precautions/ This error occurs when there is a communications error in at least one of the target Slave Units. The target Slave Units
Remarks are determined as follows:
• All Slave Units if pin 4 (REGS) on the DIP switch is set to OFF on the Master Unit when the power supply is turned
ON or the Controller is reset.
• Only registered Slave Units if pin 4 (REGS) on the DIP switch is set to ON when the power supply is turned ON or the
Controller is reset.
• You can change the event level to the observation level. If you change the level to the observation level, the Recovery
column above will be changed to "Error reset."
7-16
Source details
Minor fault Recovery
Continues. Operation
Data type
---
Correction
Refer to the communications specifi-
cations and adjust all of the cables to
suitable lengths.
Connect the cable securely. If the
cable is broken, replace it.
Connect terminating resistance only
to the ends of the trunk line.
Take actions to prevent noise.
Investigate the disconnected Slave
Unit and remove the cause of the
problem.
CJ-series CompoNet Master Unit Operation Manual for NJ-series CPU Unit (Cat. No. W493)
Event code 8460 0000 hex
CJ-series Unit Detection
timing
Error reset Log category
Communications are not possible for a disconnected
Slave Unit. The Master Unit waits for the disconnected
Slave Unit to join the network. When the cause of the error
is removed, the disconnected Slave Unit returns to normal
operation.
Name
---
Prevention
Refer to the communications specifi-
cations and adjust all of the cables to
suitable lengths.
Connect the cable securely. Check
the cable to see if it is operating prop-
erly.
Connect terminating resistance only
to the ends of the trunk line.
Take actions to prevent noise.
Make sure that the Slave Units are
not faulty, lines are not disconnected,
and the communications power is not
interrupted.
During Compo-
Net communica-
tions
System