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Chapter 5 Power Supply / CPU
5 -17
REMARK
Total available interrupt points is 8(In standard type).
-. Time driven interrupt + process driven interrupt + high speed counter driven interrupt ≤ 8 points
Interrupt signal is ignored when self-interrupt occurs more than 2 times during interrupt processing is executing.
5.4.4 Error Handling
1) Error Classification
Errors occur due to various causes such as PLC system defect, system configuration fault or abnormal operation
result. Errors are classified into fatal error mode, which stops system operation for system stability, and ordinary
error mode, which continues system operation with informing the user of its error warning.
The main factors that occurs the PLC system error are given as followings.
• PLC hardware defect
• System configuration error
• Operation error during execution of the user programs
• External device malfunction
2) Operation mode at error occurrence
In case of error occurrence, the PLC system write the error contents the corresponding flags and stops or conti
nues its operation complying with its operation mode.
(1) PLC hardware defect
The system enters into the STOP state if a fatal error such as the CPU module defect has occurred, and
continues its operation if an ordinary error such as operation error has occurred.
(2) System configuration error
This error occurs when the PLC hardware configuration differs from the configuration defined in the
K120S series. The system enters into the STOP state.
(3) Operation error during execution of the user programs
It the numeric operation error of these errors occurs during execution of the user program, its contents are
marked on the error flags and the system continues its operation. If operation time overruns the watchdog
time or I/O modules loaded are not normally controlled, the system enters into the STOP state.
Interrupt executing time
Interrupt signal (ex : rising edge)
ignored