Self-Diagnostics Function - Mitsubishi A1SJH(S8) User Manual

4. CPU MODULE
4.1.4

Self-diagnostics function

Self-diagnosis is a function that a CPU module diagnoses itself for the presence of any
abnormalities.
(1)
(2)
(3)
(4)
While turning on the programmable controller power or when an error occurred in the
PLC RUN, the error is detected and displayed, and the operation is stopped by the
self-diagnostics function, which the CPU module performs, to prevent programmable
controller malfunctions and give preventive maintenance.
The CPU module stores the error occurred last to a special register D9008 as an
error code.
The following shows contents of the error information. (The error which occurred
last):
(a) The time and date of error occurrences.................... Year, month, day, hour,
(b) Error Code................................................................ The content of the special
(c) Detailed error code.................................................... The content of the special
(d) Error step and error module installation address.......The content of the special
When detecting an error by self-diagnosis, AnSHCPU takes action in the following
modes:
• Mode wherein the programmable controller operation is stopped
• Mode wherein the programmable controller operation is continued
In addition, some errors can be skipped or stopped by setting parameters.
(a) When an operation stop error is detected by the self-diagnosis, the AnSHCPU
stops the operation at error detection, and sets the all outputs(Y) to OFF.
(b) When an error of operation continued is detected, the only part of the program
with the error is not executed while the other part is executed.
Also, in the case of module verify error, the operation is continued using the I/O
address prior to the error.
Since error occurrence and error contents are stored in the special relay (M) and
special register (D) at error detection, use in the program for preventing any
malfunctions of the programmable controller or mechanical system especially in
mode wherein the programmable controller operation is continued.
The next page shows error descriptions detected by the self-diagnosis.
4 - 10
minute, second (Clock data)
register D9008
register D9092
register D9010, D9000,
D9002