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6.17 Self-diagnostics Function
6
FUNCTIONS
(4) Error history checking
The CPU module stores 16 latest error codes. (
The failure history can be checked in the GX Developer function PLC diagnostics
mode.
The failure history can be stored even when the power is shut off using the battery
backup.
(5) CPU module operation at the time of error detection
(a) Mode at error detection
When an error is detected from the self-diagnosis, there are two types of modes
that the CPU module operation can change to.
1) CPU module calculation stop mode
At detection of an error, the CPU module stops operation and turns OFF all
external outputs of the modules set to "Clear" (default) in the "error time output
mode" in the I/O assignment setting of the PLC parameter dialog box. (The
output (Y) on the device memory is held.)
Note that the external outputs of the modules set to "Hold" in the "error time
output mode" are held. (The output (Y) of the device memory is held.)
2) CPU module calculation continue mode
At detection of an error, the CPU module executes programs other than the
one that has developed the error.
(b) Errors that can be set to continue/stop the operation
The following errors can be set to "continue/stop" the operation when they have
occurred.
1) Errors that can be set to continue/stop the operation in PLC RAS setting
of PLC parameter dialog box
• Computation error
• Extended instruction error (Setting for future extension)
• Fuse blown
• Module comparison error
• Intelligent module program execution error
• File access error
Note55
• Memory card operation error
• External power supply OFF (Setting for future extension)
For example, when the module comparison error is set to "continues", the
calculations are continued in the I/O address before the error occurred.
For details of errors, refer to Self-diagnostics list in Section 6.17 (7).
2) Error can be set to continue/stop the operation in detail setting of I/O
assignment setting of PLC parameter dialog box
• Intelligent function module error
Note55Çñ
Basic
Note6.53
The operation mode of "File access error", "Memory card operation error", and "External power
supply OFF" cannot be set for the Basic model QCPU.
Basic