Omron CJ - PROGRAMMING MANUAL 12-2009 Programming Manual page 108

Checking Programs
Type of error
1.Instruction Processing Error
2.Access Error
3.Illegal Instruction Error
4.UM (User Memory) Overflow Error
68
The following checks are performed during instruction execution.
Flag that turns ON for error
ER Flag
The Instruction Processing Error Flag
(A29508) will also turn ON if Stop
Operation is specified when an error
occurs.
AER Flag
The Access Error Flag (A29510) will
turn ON if Stop Operation is specified
when an error occurs.
Illegal Instruction Error Flag (A29514)
UM Overflow Error Flag (A29515)
Instruction Processing Errors
An instruction processing error will occur if incorrect data was provided when
executing an instruction or an attempt was made to execute an instruction out-
side of a task. Here, data required at the beginning of instruction processing
was checked and as a result, the instruction was not executed, the ER Flag
(Error Flag) will be turned ON and the EQ and N Flags may be retained or
turned OFF depending upon the instruction.
The ER Flag (error Flag) will turn OFF if the instruction (excluding input
instructions) ends normally. Conditions that turn ON the ER Flag will vary with
individual instructions. See descriptions of individual instructions in the CS/
CJ-series Programmable Controllers Programming Manual (W340) for more
details.
If Instruction Errors are set to Stop Operation in the PLC Setup, then opera-
tion will stop (fatal error) and the Instruction Processing Error Flag (A29508)
will turn ON if an instruction processing error occurs and the ER Flag turns
ON.
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.
Section 2-3
Stop/Continue operation
A setting in the PLC Setup can be used
to specify whether to stop or continue
operation for instruction processing
errors. The default is to continue opera-
tion.
A program error will be generated and
operation will stop only if Stop Opera-
tion is specified.
A setting in the PLC Setup can be used
to specify whether to stop or continue
operation for instruction processing
errors. The default is to continue opera-
tion.
A program error will be generated and
operation will stop only if Stop Opera-
tion is specified.
Fatal (program error)
Fatal (program error)