Handling Of General Flags - Mitsubishi FX3U Series Programming Manual

FX /FX Series Programmable Controllers
3U 3UC
Programming Manual - Basic & Applied Instruction Edition
6.5.2

Handling of general flags

In some types of applied instructions, the following flags operate:
Examples:
These flags turn ON or OFF every time various instructions turn ON, but do not change when various
instructions turn OFF not driven or when errors have occurred.
Because these flags turn ON or OFF in many instructions, the ON/OFF status of flags change every time
such instructions are executed.
Program flag contacts just under each instruction while referring to the examples below.
1. Program containing many flags (example of instruction execution complete flag M8029)
When two or more instruction execution complete flags M8029 are programmed together for applied
instructions, it is difficult to judge by the contents of which instruction executes which flag, and it is disabled to
normally activate each flag corresponding to each instruction.
For using flags in any positions other than just under applied instructions, refer to the next page.
Good example
Bad example
148
M8020: Zero flag
M8029: Instruction execution complete flag
M8090: Block comparison signal
M8329: Instruction execution abnormal complete flag
M8000
Execution is
M8029 works as
a flag to indicate
that execution of
DSW is
completed.
X000
M0
M8029 works as
a flag to indicate
that execution of
DPLSY is
Execution is
completed.
M8029 works as
M8029
a flag to indicate
that execution of
Execution is
DPLSY (on the
completed
lower side) is
completed.
M8000
M8029 works as
X000
a flag to indicate
that execution of
DSW is
completed.
M0
M8029 works as
a flag to indicate
M8029
that execution of
DPLSY (on the
upper side) is
Execution is
completed.
completed
M1
M8021: Borrow flag
M8328: Instruction non-execution flag
FNC 72
X10 Y10
DSW
M8029
FNC 22
MUL
completed
M0
SET
FNC 57
K1000 D20
DPLSY
M8029
RST
completed
RST
FNC 72
X10 Y10
DSW
M0
SET
FNC 57
K1000 D20
DPLSY
FNC 22
D0 K10
MUL
FNC 57
K1000 D22
DPLSY
6 What to Understand before Programming
6.5 General Rules for Applied Instructions
M8022: Carry flag
D0 K1
D0 K10 D20
Y000
M0
Program for DPLSY instruction
M0
(on the upper side)
D0 K1
DPLSY instruction
Y000
(on the upper side)
Program for DSW
D20
instruction
DPLSY instruction
Y001
(on the lower side)