Arithmetic Flags; Step Flag; First Cycle Flag - Omron SYSMAC CV Series Operation Manual

Auxiliary Area
3-6-51

Arithmetic Flags

! Caution
Carry Flag, CY
Greater Than Flag, GR
Equals Flag, EQ
Less Than Flag, LE
Negative Flag, N
Overflow Flag, OF
Underflow Flag, UF
! Caution
3-6-52

Step Flag

3-6-53

First Cycle Flag

word that is non-existent. When the ER Flag is ON, the current instruction
will not be executed.
The following flags are used in data shifting, arithmetic calculation, and com-
parison instructions. They are generally referred to only by their two-letter
abbreviations.
These flags are all reset when the END instruction is executed, and therefore
cannot be monitored from a Peripheral Device.
Refer to 5-14 Shift Instructions , 5-16 Comparison Instructions , 5-18 BCD Cal-
culation Instructions , and 5-19 Binary Calculation Instructions for details.
Bit A50004 is turned ON when there is a carry in the result of an arithmetic
operation or when a rotate or shift instruction moves a "1" into CY. The con-
tent of CY is also used in some arithmetic operations, e.g., it is added or sub-
tracted along with other operands. This flag can be set and cleared from the
program using the SET CARRY and CLEAR CARRY instructions. This Flag
is also used by the I/O READ and I/O WRITE instructions. Refer to page 405
for details.
Bit A50005 is turned ON when the result of a comparison shows the first of
two operands to be greater than the second.
Bit A50006 is turned ON when the result of a comparison shows two oper-
ands to be equal or when the result of an arithmetic operation is zero.
Bit A50007 is turned ON when the result of a comparison shows the first of
two operands to be less than the second.
Bit A50008 is turned ON when the highest bit in the result of a calculation is
ON.
Bit A50009 is turned ON when the absolute value of the result is greater than
the maximum value that can be expressed.
Bit A50010 is turned ON when absolute value of the result is less than the
minimum value that can be expressed.
The previous seven flags are cleared when END(001) is is executed.
Bit A50012 is turned ON for one cycle when step execution is started with the
STEP(008) instruction.
When ladder-only programming is used, bit A50015 turns ON when PC op-
eration begins and then turns OFF after one cycle of the program. When
SFC programming is used, A50015 turns ON for one cycle at the beginning
of action program execution. A50015 also turns ON at the beginning of
scheduled interrupt execution. The First Cycle Flag is useful in initializing
counter values and other operations. An example of this is provided in 5-13
Timer and Counter Instructions .
Section 3-6
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