60
Here, 0500 will be turned ON for one cycle after 0000 goes ON. The next
time DIFU(13) 0500 is executed, 0500 will be turned OFF, regardless of the
status of 0000. With the DIFFERENTIATE DOWN instruction, 0501 will be
turned ON for one cycle after 0001 goes OFF (0501 will be kept OFF until
then) and will be turned ON the next time DIFD(14) is executed.
4-7-2 KEEP
The KEEP instruction is used to maintain the status of the operand bit based
on two execution conditions. To do this, the KEEP instruction is connected to
two instruction lines. When the execution condition at the end of the first in-
struction line is ON, the operand bit of the KEEP instruction is turned ON.
When the execution condition at the end of the second instruction line is ON,
the operand bit of the KEEP instruction is turned OFF. The operand bit for the
KEEP instruction will maintain its ON or OFF status even if it is located in an
interlocked section of the diagram and the execution condition for the INTER-
LOCK instruction is ON.
In the following example, HR 000 will be turned ON when 0002 is ON and
0003 is OFF. HR 000 will then remain ON until either 0004 or 0005 turns ON.
S:set
R: reset
KEEP(11)
HR 000
0002
0004
0003
0005
Address
Instruction
Operands
0000
LD
0002
0001
AND NOT
0003
0002
LD
0004
0003
OR
0005
0004
KEEP(11)
HR
000
4-7-3
Self-maintaining Bits (Seal)
Although the KEEP instruction can be used to create self maintaining bits, it
is sometimes necessary to create self maintaining bits in another way so that
they can be turned OFF when in an interlocked section of a program.
To create a self maintaining bit, the operand bit of an OUTPUT instruction is
used as a condition for the same OUTPUT instruction in an OR setup so that
the operand bit of the OUTPUT instruction will remain ON or OFF until
changes in other bits occur. At least one other condition is used just before
the OUTPUT instruction to function as a reset. Without this reset, there would
be no way to control the operand bit of the OUTPUT instruction.
The above diagram for the KEEP instruction can be rewritten as shown be-
low. The only difference in these diagrams would be their operation in an in-
terlocked program section when the execution condition for the INTERLOCK
instruction was ON. Here, just as in the same diagram using the KEEP in-
struction, two reset bits are used, i.e., HR 000 is turned OFF by turning ON
both 0004 and 0005.
0002
0003
HR 000
HR 000
0004
0005
Address
Instruction
Operands
0000
LD
0002
0001
AND NOT
0003
0002
OR
HR
000
0003
AND NOT
0004
0004
OR NOT
0005
0005
OUT
HR
000
Controlling Bit Status
Section 4-7
Содержание SYSMAC C20K
Страница 1: ...Cat No W146 E1 5 Programmable Controllers SYSMAC C20K C28K C40K C60K ...
Страница 2: ...K type Programmable Controllers OPERATION MANUAL Revised July 1999 ...
Страница 3: ...iv ...
Страница 5: ...vi ...
Страница 19: ...7 SECTION 2 Hardware Considerations 2 1 Introduction 2 2 Indicators 2 3 PC Configuration ...
Страница 225: ...Cat No W146 E1 5 Note Specifications subject to change without notice Printed in Japan Authorized Distributor ...