70
4-4-4 OUTPUT and OUTPUT NOT
The simplest way to output the results of combining execution conditions is to
output it directly with the OUTPUT and OUTPUT NOT. These instructions are
used
to control the status of the designated operand
bit according to the execu
-
tion
condition. With the OUTPUT instruction, the operand bit will be turned ON
as
long as the execution condition is ON
and will be turned OFF as long as the
execution
condition is OFF
. With the OUTPUT NOT instruction, the operand bit
will be turned ON as long as the execution condition is OFF and turned OFF as
long
as the execution condition is ON. These appear as shown below
. In mne
-
monic code, each of these instructions requires one line.
00000
00201
00200
00001
Address Instruction Operands
00000 LD 00000
00001 OUT 00200
Address Instruction Operands
00000 LD 00001
00001 OUT NOT 00201
In
the above examples, IR 00200 will
be ON as long as IR 00000 is ON and IR
00201
will be OFF as long as IR 00001
is ON. Here, IR 00000 and IR 00001 will
be
input bits and IR 00200 and IR 00201 output bits assigned to the Units
con
-
trolled
by the PC, i.e., the signals coming in through the input
points assigned IR
00000
and IR 00001 are controlling the output points assigned IR 00200 and IR
00201, respectively.
The length of time that a bit is ON or OFF can be controlled by combining the
OUTPUT
or OUTPUT NOT instruction with TIMER instructions.
Refer to Exam
-
ples under 5-14-1 TIMER – TIM for details.
4-4-5 The END Instruction
The
last instruction required to complete a simple
program is the END instruc
-
tion.
When the CPU cycles the program, it executes all
instruction up to the first
END
instruction before returning to
the beginning of the program and beginning
execution again. Although an END instruction can be placed at any point in a
program, which is sometimes done when debugging, no instructions past the
first
END instruction will be executed until it is removed. The number
following
the END instruction in the mnemonic code is its function code, which is used
when
inputted most instruction
into the PC. These are described later
. The END
instruction
requires no operands
and no conditions can be placed on the same
instruction line with it.
Instruction
00000 00001
END(01)
Program execution
ends here.
Address Instruction Operands
00000 LD 00000
00001 AND NOT 00001
00002 Instruction
00003 END(01) ---
If
there is no END instruction anywhere in the program, the program
will not be
executed at all.
Basic Ladder Diagrams Section 4-4
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