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Checking Programs Section 2-3
Illegal Access Errors
Illegal access errors indicate that the wrong area was accessed in one of the
following ways when the address specifying the instruction operand was
accessed.
a) A read or write was executed for a parameter area.
b) A write was executed in a memory area that is not mounted (see note).
c) A write was executed in an EM area specified as EM File Memory.
d) A write was executed in a read-only area.
e) The value specified in an indirect DM/EM address in BCD mode was
not BCD (e.g., *D000001 contains #A000).
Instruction processing will continue and the Error Flag (ER Flag) will not turn
ON if an access error occurs, but the Access Error Flag (AER Flag) will turn
ON.
Note An access error will occur for the following:
• When a specified EM address exceeds 32767 (example: E32768) for
the current bank.
• The final bank (example: C) is specified for an indirect EM address in
BIN mode and the specified word contains 8000 to FFFF Hex (exam-
ple: @EC_00001 contains #8000).
• The current bank (example: C) is specified for an indirect EM address
in BIN mode and the specified words contains 8000 to FFFF Hex (ex-
ample: @EC_00001 contains #8000)
• An IR register containing the internal memory address of a bit is used
as a word address or an IR containing the internal memory address of
a word is used as a bit address.
If Instruction Errors are set to Stop Operation in the PLC Setup, then opera-
tion will stop (fatal error) and the “Illegal Access Error Flag” (A29510) will turn
ON if an illegal access error occurs and the AER Flag turns ON.
Note The Access Error Flag (AER Flag) will not be cleared after a task is executed.
If Instruction Errors are set to Continue Operation, this Flag can be monitored
until just before the END(001) instruction to see if an illegal access error has
occurred in the task program. (The status of the final AER Flag after the entire
user program has been executed will be monitored if the AER Flag is moni-
tored on a Programming Console.)
Other Errors
Illegal Instruction Errors
Illegal instruction errors indicate that an attempt was made to execute instruc-
tion data other than that defined in the system. This error will normally not
occur as long as the program is created on a CS/CJ-series Programming
Device (including Programming Consoles).
In the rare even that this error does occur, it will be treated as a program error,
operation will stop (fatal error), and the Illegal Instruction Flag (A29514) will
turn ON.
UM (User Memory) Overflow Errors
UM overflow errors indicate that an attempt was made to execute instruction
data stored beyond the last address in the user memory (UM) defined as pro-
gram storage area. This error will normally not occur as long as the program is
created on a CS/CJ-series Programming Device (including Programming
Consoles).
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