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Failure Diagnosis Instructions Section 3-28
When FALS(007) is executed with N set to an FAL number (1 to 511) that is
equal to the content of A529 (the system-generated FAL/FALS number), a
fatal error will be generated with the error code and error details code speci-
fied in S and S+1. The following processing will be performed at the same
time:
1,2,3... 1. The specified error code will be written to A400.
2. The error code and the time that the error occurred will be written to the
Error Log Area (A100 through A199).
3. The appropriate Auxiliary Area Flags are set based on the error code and
error details.
4. The ERR Indicator on the CPU Unit will light and PLC operation will be
stopped.
5. The fatal error message for the specified system error will be displayed on
the Programming Device.
Note (1) The value of A529 (the system-generated FAL/FALS number) is a dummy
FAL number (FAL, FALS, and FPD numbers are shared.) used when a
non-fatal error is generated intentionally by the system. This number is a
dummy FAL number, so it is not reflected in the error code.
When it is necessary to generate two or more system errors, different er-
rors can be generated by executing the FAL/FALS/FPD instructions more
than once with the same values in A529 and N, but different values in S
and S+1.
(2) If a more serious error (including a system-generated fatal error or anoth-
er FALS(007) error) occurs at the same time as the FALS(007) instruc-
tion, the more serious error’s error code will be written to A400.
(3) To clear a system error generated by FALS(007), turn the PLC OFF and
then ON again. The PLC can be kept ON, but the same processing will
be required to clear the error as if the specified error had actually oc-
curred. Refer to information on troubleshooting in the CP Series Opera-
tion Manual for details.
(4) The following table shows how the IOM Hold Bit affects the status of I/O
memory and the status of outputs on Output Units after a fatal system er-
ror has been generated with FALS(007).
Note Unlike user-defined fatal errors, system errors generated by FALS(007) will
clear I/O memory if the IOM Hold Bit is OFF. The following areas will be
cleared: CIO Area, Work Area, Timer Flags and PVs, Index Registers, and
Data registers.
IOM Hold Bit
(A500.12)
Status of I/O memory Status of outputs on Output
Units
ON Retained OFF
OFF Cleared OFF
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