1 Overview
1-16
CJ2 CPU Unit Hardware User’s Manual
Self-diag-
nosis and
Restora-
tion
(Contin-
ued from
previous
page)
Non-fatal Error
Detection
System FAL Error Detec-
tion (User-defined non-
fatal error)
This function generates a non-fatal (FAL) error when the user-defined condi-
tions are met in program.
Duplicate Refreshing Error
Detection
This function detects an error when an immediate refreshing Instruction in an
interrupt task is competing with I/O refreshing of a cyclic task.
Basic I/O Unit Error Detec-
tion
This function detects the errors in Basic I/O Units.
Backup Memory Error
Detection
This function detects errors in the memory backup of the user programs and
parameter area (backup memory).
PLC Setup Error Detection This function detects setting errors in the PLC Setup.
CPU Bus Unit Error Detec-
tion
This function detects an error when there is an error in data exchange between
the CPU Unit and a CPU Bus Unit.
Special I/O Unit Error
Detection
This function detects an error when there is an error in data exchange between
the CPU Unit and a Special I/O Unit.
Tag Memory Error Detec-
tion
This function detects errors in tag memory.
Battery Error Detection This function detects an error when a battery is not connected to the CPU Unit
or when the battery voltage drops.
CPU Bus Unit Setting
Error Detection
This function detects an error when the model of a CPU Bus Unit in the regis-
tered I/O tables does not agree with the model that is actually mounted in the
PLC.
Special I/O Unit Setting
Error Detection
This function detects an error when the model of a Special I/O Unit in the regis-
tered I/O tables does not agree with the model of Unit that is actually mounted.
Memory Error Detection This function detects errors that occur in memory of the CPU Unit.
I/O Bus Error Detection This function detects errors has occur in data transfers between the Units
mounted in Rack slots and the CPU Unit and detects when the End Cover is
not connected to the CPU Rack or an Expansion Rack.
Unit/Rack Number Dupli-
cation Error
This function detects an error when the same unit number is set for two or more
Units, the same word is allocated to two or more Basic I/O Units, or the same
rack number is set for two or more Racks.
Too Many I/O Points Error
Detection
This function detects an error when the total number of I/O points set in the I/O
tables or the number of Units per Rack exceeds the specified range.
I/O Setting Error Detection This function detects an error when the number of Units in the registered I/O
tables does not agree with the actual number of Units that is mounted, or an
Interrupt Unit has been connected in the wrong position, i.e., not in slot 0 to 3.
Fatal Error
Detection
Program Error Detection This function detects errors in programs.
Instruction Processing
Error Detection
This function detects an error when the given data value is invalid when execut-
ing an instruction, or execution of instruction between tasks was attempted.
Indirect DM/EM BCD
Error Detection
This function detects an error when an indirect DM/EM address in BCD mode
is not BCD.
Illegal Area Access
Error Detection
This function detects an error when an attempt is made to access an illegal
area with an instruction operand.
No END Error Detec-
tion
This function detects an error when there is no END instruction at the end of
the program.
Task Error Detection This function detects an error when there are no tasks that can be executed in
a cycle, there is no program for a task, or the execution condition for an inter-
rupt task was met but there is no interrupt task with the specified number.
Differentiation Over-
flow Error Detection
This function detects an error when too many differentiated instructions are
entered or deleted during online editing (131,072 times or more).
Invalid Instruction Error
Detection
This function detects an error when an attempt is made to execute an instruc-
tion that is not defined in the system.
User Program Area
Overflow Error Detec-
tion
This function detects an error when instruction data is stored after the last
address in user program area.
Cycle Time Exceeded
Error Detection
This function monitors the cycle time (10 to 40,000 ms) and stops the operation
when the set value is exceeded.
Function Description
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