Omron CJ1W-DRM21 - Page 285

9-55
9 Troubleshooting and Maintenance
CJ-series DeviceNet Units Operation Manual for NJ-series CPU Unit(W497)
9-4 Event Logs
9
9-4-3 Error Descriptions
Event name Bus Off Detected Event code 84740000 hex
Meaning A Bus Off error occurred (i.e., communications stopped because there were too many communications errors).
Source PLC Function Module Source details CJ-series Unit Detection
timing
When the I/O
connection is
established or
DeviceNet com-
munications are
performed
Error attributes Level Minor fault Recovery Cycle the power
supply or reset
the Controller.
Log category System
Effects User program Continues. Operation The DeviceNet Unit is offline. Communications will not
operate. Error responses are returned to all communica-
tions requests. Data refreshing with the CPU Unit contin-
ues.
System-defined
variables
Variable Data type Name
None --- ---
Cause and
correction
Assumed cause Correction Prevention
The master and slave have different
baud rates.
Correct the settings so that the mas-
ter and slaves use the same baud
rate.
Set the master and slaves to the
same baud rate.
Communications cable lengths (trunk
line and branch lines) are unsuitable.
Refer to the communications specifi-
cations and adjust all of the communi-
cations cables to suitable lengths.
Refer to the communications specifi-
cations and adjust all of the communi-
cations cables to suitable lengths.
A communications cable is discon-
nected or loose.
Connect the communications cable
securely. If the communications cable
is broken, replace it.
Connect the communications cable
securely. Check the communications
cable to see if it is operating properly.
The terminating resistance is some-
where other than the ends of the trunk
line.
Connect terminating resistance only
to the ends of the trunk line.
Connect terminating resistance only
to the ends of the trunk line.
Noise Implement noise countermeasures. Implement noise countermeasures.
Attached
information
None
Precautions/
Remarks
None