Panasonic FP2 ET-LAN Technical Manual page 250

Operation mode
The contents of special internal relays R9020 to R9027 are expressed as 2-character hexadecimal
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values.
The user can check the settings of the mode selector switches on the CPU unit
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(RUN/PROG./REMOTE), whether normal operation or test operation is being used, and other elements.
Values are read in binary notation, as shown below.
Error flag
The statuses of the eight error flags (special internal relays) R9000 to R9007 are expressed as 2-
character hexadecimal values. They are read using binary notation, as shown below.
Self-diagnostic error code
If an error occurs, the self-diagnosis error code is expressed as a 4-digit hexadecimal value. Please be
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careful, since self-diagnosis error codes are normally treated as decimal values.
For example, if the content is read as "2D00" in hexadecimal format, the self-diagnosis error code will
be "2D". In decimal notation it will be read as "45" (Operation error).
If no error has occurred, the value will be "0000".
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