Omron CJ1W-SCU32 Operation Manual page 326

9 Troubleshooting and Maintenance
Event name Overrun Error
Meaning An overrun occurred.
Source PLC Function Module
Error attributes Level
Effects User program
System-defined Variable
variables
None
Cause and Assumed cause
correction
In Serial Gateway Mode or Protocol
Macro Mode:
• The reception circuits in the Serial
Communications Unit are faulty.
• A transmission error occurred due
to noise or other factors.
No-protocol Mode:
• The reception buffer received more
than 259 bytes of data before the
SerialRcv/SerialRcvNoClear
instruction was executed.
During Loopback Test
• Loopback test jig failure.
• Noise
• The communications circuits in the
Serial Communications Unit are
faulty.
Attached Attached information 1: Port number where error was detected
information
Precautions/ After an overrun error occurs, you can return the Overrun Error Flag for the Serial Communications Unit to FALSE by
Remarks cycling the power supply, resetting the Controller, restarting the Serial Communications Unit, or restarting the port.
9-48
Source details
Observation Recovery
Continues. Operation
Data type
---
Correction
• Perform a loopback test in the serial
communications mode and check
the transmission lines. If an error
occurs during testing, replace the
Serial Communications Unit.
• Implement noise countermeasures.
Increase the setting for the number
of resends in the device that sent
the command. If required, perform
retry processing for communica-
tions.
Cycle the power supply, reset the
Controller, or restart the Unit and
clear the receive buffer.
• Correct any mistakes in wiring the
loopback test jig.
• Implement noise countermeasures.
• Replace the Unit.
CJ-series Serial Communications Units Operation Manual for NJ-series CPU Unit(W494)
Event code 8469 0000 hex
CJ-series Unit Detection
timing
--- Log category
Not affected.
Name
---
Prevention
Perform countermeasures in
advance.
• Check the wiring of the loopback
test jig.
• Use the Unit away from sources of
noise. Implement noise counter-
measures.
After serial com-
munications start
System