Differentiate Up And Differentiate Down; Keep; Self-Maintaining Bits (Seal) - Omron C200HX Operation Manual

Controlling Bit Status

4-8-1 DIFFERENTIATE UP and DIFFERENTIATE DOWN

00000
00001

4-8-2 KEEP

00002
00004
00005

4-8-3 Self-maintaining Bits (Seal)

DIFFERENTIATE UP and DIFFERENTIATE DOWN instructions are used to
turn the operand bit ON for one cycle at a time. The DIFFERENTIATE UP
instruction turns ON the operand bit for one cycle after the execution condition
for it goes from OFF to ON; the DIFFERENTIATE DOWN instruction turns ON
the operand bit for one cycle after the execution condition for it goes from ON to
OFF. Both of these instructions require only one line of mnemonic code.
DIFU(13) 00200
DIFD(14) 00201
Here, IR 00200 will be turned ON for one cycle after IR 00000 goes ON. The next
time DIFU(13) 00200 is executed, IR 00200 will be turned OFF, regardless of the
status of IR 00000. With the DIFFERENTIATE DOWN instruction, IR 00201 will
be turned ON for one cycle after IR 00001 goes OFF (IR 00201 will be kept OFF
until then), and will be turned OFF the next time DIFD(14) 00201 is executed.
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 instruction
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 instruc-
tion will maintain its ON or OFF status even if it is located in an interlocked sec-
tion of the diagram.
In the following example, HR 0000 will be turned ON when IR 00002 is ON and IR
00003 is OFF. HR 0000 will then remain ON until either IR 00004 or IR 00005
turns ON. With KEEP, as with all instructions requiring more than one instruction
line, the instruction lines are coded first before the instruction that they control.
00003
S: set input
R: reset input
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.
Address Instruction
00000 LD
00001 DIFU(13)
Address Instruction
00000 LD
00001 DIFD(14)
Address Instruction
00000 LD
KEEP(11)
00001 AND NOT
HR 0000 00002 LD
00003 OR
00004 KEEP(11)
Section 4-8
Operands
00000
00200
Operands
00001
00201
Operands
00002
00003
00004
00005
HR 0000
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