Instruction Execution Checks - Omron SYSMAC CJ - REFERENCE MANUAL 08-2008 Reference Manual

Instruction Execution Checks

1-2 Instruction Execution Checks
1-2-1 Errors Occurring at Instruction Execution
1-2-2 Fatal Errors (Program Errors)
An instruction's operands and placement are checked when an instruction is
input from a Peripheral Device or a program check is performed from a
Peripheral Device (other than a Programming Console), but these are not final
checks. The following four errors can occur when an instruction is executed.
Instruction Processing Error (ER Flag ON)
Normally, Instruction Processing Errors are non-fatal errors, but the PLC
Setup can be set to treat Instruction Processing Errors as fatal errors. If this
setting has been made, the Instruction Processing Error Flag (A29508) will be
turned ON and program execution will stop when an Instruction Processing
Error occurs.
Access Error (AER Flag ON)
Normally, Access Errors are non-fatal errors, but the PLC Setup can be set to
treat these errors as fatal errors. If this setting has been made, the Illegal
Access Error Flag (A29510) and the Indirect DM/EM BCD Error Flag
(A29509) will be turned ON and program execution will stop when an Access
Error occurs.
Illegal Instruction Error
The Illegal Instruction Error Flag (A29514) will be turned ON and program
execution will stop when this error occurs.
UM (User Program Memory) Overflow Error
The UM Overflow Error Flag (A29515) will be turned ON and program execu-
tion will stop when this error occurs.
Program execution will be stopped when one of the following program errors
occurs. When a program error has occurred, the task number of the task that
was being executed when program execution was stopped is written to A294
and the program address is written to A298 and A299.
Use the contents of these words to locate the program error and correct it as
necessary.
Address
A294 The task number of the current task is written to this word when pro-
gram execution is stopped because of a program error.
Cyclic tasks have task numbers 0000 to 001F (cyclic tasks 0 to 31).
Interrupt tasks have task numbers 8000 to 80FF (interrupt tasks 0 to
255).
A298 and The current program address is written to these words when program
A299 execution is stopped because of a program error.
A299 contains the leftmost digits of the program address and A298
contains the rightmost digits of the program address.
Section 1-2
Description
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