Self-Diagnostics Functions - Mitsubishi MELSEC-A A2USHCPU-S1 User Manual

4. CPU MODULE
4.1.4

Self-diagnostics functions

Self-diagnostics is a function with which a CPU module diagnoses itself for the presence
of any abnormalities.
(1)
(2)
(3)
In turning on the power supply to the PLC or when an abnormality occurred while the
PLC is running, the CPU module's self-diagnostics processing prevents malfunctions
of the PLC. It also performs preventive maintenance by detecting the abnormality,
displaying an error indication, halting the operation of the CPU module, and so on.
The CPU module stores the error occurred last to a special register D9008 as an
error code, and stores further detailed error code to a special register D9091.
Even with the power-off, the latest error information and 15 errors in the past, that is
16 errors, are stored by battery backup.Contents of errors can be checked by the
peripheral device. For the method of checking the errors in the past, refer to Selfdiag-
nostics of the Operating manual for peripheral device.
Reset (All clear) in the past error information can be performed by operating "latch
clear" in the CPU module.
Contents of the error information are shown below: (The error which occurred last)
(a) The time and date of occurrences of
errors .................................................... Year, month, day, hour, minute, second
(b) Error Code ........................................... The content of the special register
(c) Detailed error code ............................. The content of the special register
(d) Error step .............................................. The content of the special register
Note that the following three error codes show the contents different from the
contents usually shown in detailed error code and in error step when monitoring by
the peripheral device.
(Clock data)
D9008
D9091
D9010
4 - 13