Self-Diagnostics Function; Self-Diagnostics Timing; Check Method Of Error - Mitsubishi Electric MELSEC iQ-R Series User Manual

15.2

Self-Diagnostics Function

This function (the CPU module itself) checks if a problem exists in the CPU module.

Self-diagnostics timing

If an error occurs when the CPU module is powered on or while it is in the RUN/STOP state, the CPU module detects, and
displays it, and stops operation. However, depending on the error occurrence status or the instruction to execute, the CPU
module may not be able to detect the error. Configure safety circuits external to the programmable controller to ensure that
the entire system operates safely even in such a case.

Check method of error

This section describes the check methods when error occurs.
Check method using the special relay and special register
When the CPU module detects an error, it turns SM0 (Latest self-diagnostic error (including annunciator ON)) and SM1
(Latest self-diagnostic error (not including annunciator ON)) on and stores the error code corresponding to the error definition
in SD0 (Latest self-diagnostics error code). If multiple errors are detected, the latest error code is stored in SD0. Use SM0,
SM1, and SD0 on the program for the CPU module or mechanical interlock. Besides, the error code up to 16 pieces for the
error contents being currently generated will be stored into SD10 to SD25 (Self-diagnostic error number). (The error code for
the error content of 17th piece on and after will not be stored.)
Check method using LED
The error occurrence conditions can be checked through the lighting conditions of ERROR LED. ( Page 533 LED status
of the CPU module)
Check method using the engineering tool
The error conditions for the overall system, error or event history being currently generated can be checked on the Module
diagnostics window. ( GX Works3 Operating Manual)
■Existing errors
Up to 16 errors (descriptions of errors) currently existing on the CPU module can be displayed.
additional error occurs after a stop error, the error information is not updated.
*1 The maximum number of displayable errors is 15 for continuation errors and 1 for stop errors. When 15 continuation errors are displayed
and another one occurs, description of the new error is not displayed. Also, when an error with the same code has already been
displayed, the date and time of occurrence and detailed information of the relevant error are not updated.
■Error history
Occurred errors is logged in the event history ( Page 211 Event History Function)
The event history is updated only when a battery error occurs, independent of the operating status of the CPU module. Also,
when a battery error is detected after the occurrence of a stop error, the information on existing errors is not refreshed, and
only the event history is updated.
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15.2 Self-Diagnostics Function
* 1
However, even when an