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Troubleshooting Section 10-2
■ CPU Standby
Detection of Special I/O Units and CPU Bus Units has not been completed.
• If a CPU Bus Unit has not started normally, check the Unit Setup.
• If a Special I/O Unit is not detected, replace the Special I/O Unit.
10-2-3 Fatal Errors
■ CPU Unit Indicators
There may be a CPU error or a fatal error if operation stops (i.e., the RUN indi-
cator turns OFF) and the ERR/ALM indicator lights.
Data on fatal errors is displayed on the Error Tab Page of the CX-Program-
mer’s PLC Error Window.
Take corrective actions after checking error details based on the CX-Program-
mer display message together with the Auxiliary Area Error Flags and error
information.
Note 1. Errors are listed in order with the most serious errors first.
2. If two or more errors occur at the same time, the most serious error code
will be stored in A400.
3. I/O memory will be cleared if a fatal error occurs (except those created with
FALS instructions).
4. I/O memory will be held when the I/O Memory Hold Bit is ON, but outputs
will be turned OFF.
POWER Lit
RUN Not lit
ERR/ALM Lit
INH ---
PRPHL ---
BKUP ---
POWER
RUN
INH
PRPHL
BK UP
ERR/AL