Omron HOME SECURITY SYSTEM - MOTION SENSOR FQM1-MMA21 - Manual (Page 270)

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Error Processing Section 9-2
message and related Auxiliary Area flags/words and correct the cause of the
error.
Errors are listed in order of importance. When two or more errors occur at the
same time, the more serious error’s error code will be recorded in A400.
The I/O memory will be cleared when a fatal error other than FALS occurs.
(The I/O memory will not be cleared when FALS is executed to generate a
fatal error.)