Cpu Standby Errors; Recovery Processing Flow; Error Causes And Remedies - Omron CJ2 CPU UNIT User Manual

6 Troubleshooting

CPU Standby Errors

When a CJ-series PLC is turned ON, the CPU starts cyclic servicing and enters RUN mode only after
all Special I/O Units and CPU Bus Units have been detected. If the startup mode is RUN or MONITOR
mode, the CPU will remain on standby until all Units have been detected.
POWER
Lit. Not lit.

Recovery Processing Flow

CPU standby
Check the location of
the error.
Check the
connection status.
Replace the Unit.
Is the error cleared?
Restart the System.

Error Causes and Remedies

Suspected cause of
error
Faulty connection at Unit
(at a connector)
Unit failure
The remote I/O power
supply is OFF or there is
no terminator for SYSMAC
BUS.
6-8
RUN ERR/ALM
Not lit.
Use the I/O table verification procedure (refer to 6-1-5 I/O
Table Verification) to check the location where the error
occurred.
Check the connections to the Special I/O Units and CPU Bus Units.
Replace the Unit, or remove the Unit and check
whether the error is cleared (to determine that the
Unit that was replaced or removed just before the
error was cleared was the problem).
No
Yes
Confirmation method
Check the insertion at the
connector. Restart the Unit
and check whether the error
is cleared.
Replace the Unit that is
causing the standby (the
undetected Unit). If the error
is not cleared, remove the
Units in order until the status
returns to normal.
Check whether the power is
turned ON. Check the termi-
nator settings.
Error flag Error code
None None
Remedy
Tighten the screws.
• Replace the Special I/O Unit
or Interrupt Unit for which
"$" is displayed when the I/O
tables are read.
• Replace the failed Unit.
Turn ON the power or set the
terminators. If the error is not
cleared, replace the Unit.
CJ2 CPU Unit Hardware User's Manual
Error infor-
mation
None
Prevention of
recurrence
Same as at the left.
(Determined by the
cause of the failure.)
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