Omron CS1D DUPLEX SYSTEM - 10-2009 Operation Manual page 356

Condition Flags
Name
Error Flag P_ER
Access Error Flag P_AER
Carry Flag P_CY
Greater Than Flag P_GT
Equals Flag P_EQ
Less Than Flag P_LT
Negative Flag P_N
Overflow Flag P_OF
Underflow Flag P_UF
Greater Than or P_GE
Equals Flag
Not Equal Flag P_NE
Less Than or P_LE
Equals Flag
Always ON Flag P_On
Always OFF Flag P_Off
Using the Condition Flags
320
Refer to the description of the instruction for complete details on the operation
of the Condition Flags for a particular instruction.
Symbol Label
ER Turned ON when the operand data in an instruction is incorrect (an
instruction processing error) to indicate that an instruction ended
because of an error.
When the PLC Setup is set to stop operation for an instruction error
(Instruction Error Operation), program execution will be stopped and
the Instruction Processing Error Flag (A29508) will be turned ON
when the Error Flag is turned ON.
AER Turned ON when an Illegal Access Error occurs. The Illegal Access
Error indicates that an instruction attempted to access an area of
memory that should not be accessed.
When the PLC Setup is set to stop operation for an instruction error
(Instruction Error Operation), program execution will be stopped and
the Instruction Processing Error Flag (A429510) will be turned ON
when the Access Error Flag is turned ON.
CY Turned ON when there is a carry in the result of an arithmetic opera-
tion or a "1" is shifted to the Carry Flag by a Data Shift instruction.
The Carry Flag is part of the result of some Data Shift and Symbol
Math instructions.
> Turned ON when the first operand of a Comparison Instruction is
greater than the second or a value exceeds a specified range.
= Turned ON when the two operands of a Comparison Instruction are
equal the result of a calculation is 0.
< Turned ON when the first operand of a Comparison Instruction is less
than the second or a value is below a specified range.
N Turned ON when the most significant bit (sign bit) of a result is ON.
OF Turned ON when the result of calculation overflows the capacity of the
result word(s).
UF Turned ON when the result of calculation underflows the capacity of
the result word(s).
= Turned ON when the first operand of a Comparison Instruction is
greater than or equal to the second.
< > Turned ON when the two operands of a Comparison Instruction are
not equal.
= Turned ON when the first operand of a Comparison Instruction is less
than or equal to the second.
ON Always ON. (Always 1.)
OFF Always OFF. (Always 0.)
The Condition Flags are shared by all of the instructions, so their status may
change often in a single cycle. Be sure to read the Condition Flags immedi-
ately after the execution of instruction, preferably in a branch from the same
execution condition.
Instruction A
The result from instruction A is
reflected in the Equals Flag.
Instruction B
Section 8-20
Function
Instruction Operand
LD
Instruction A
=
AND
Instruction B