Omron SYSMAC CV Series Operation Manual page 93

Mnemonic Code
AND LOAD
0000
00
0000
01
Although simple in appearance, the diagram below requires an AND LOAD
instruction.
0000
02
0000
03
The two logic blocks are indicated by dotted lines. Studying this example shows
that an ON execution condition will be produced when: either of the conditions in
the left logic block is ON (i.e., when either CIO 000000 or CIO 000001 is ON) and
either of the conditions in the right logic block is ON (i.e., when either
CIO 000002 is ON or CIO 000003 is OFF).
The above ladder diagram cannot be converted to mnemonic code using AND
and OR instructions alone. If an AND between CIO 000002 and the results of an
OR between CIO 000000 and CIO 000001 is attempted, the OR NOT between
CIO 000002 and CIO 000003 is lost and the OR NOT ends up being an OR NOT
between just CIO 000003 and the result of an AND between CIO 000002 and the
first OR. What we need is a way to do the OR (NOT)'s independently and then
combine the results.
To do this, we can use the LOAD or LOAD NOT instruction in the middle of an
instruction line. When LOAD or LOAD NOT is executed in this way, the current
execution condition is saved in special buffers and the logic process is begun
over. To combine the results of the current execution condition with that of a pre-
vious "unused" execution condition, an AND LOAD or an OR LOAD instruction is
used. Here "LOAD" refers to loading the last unused execution condition. An un-
used execution condition is produced by using the LOAD or LOAD NOT instruc-
tion for any but the first condition on an instruction line.
Analyzing the above ladder diagram in terms of mnemonic instructions, the
condition for CIO 000000 is a LOAD instruction and the condition below it is an
OR instruction between the status of CIO 000000 and that of CIO 000001. The
condition at CIO 000002 is another LOAD instruction and the condition below is
an OR NOT instruction, i.e., an OR between the status of CIO 000002 and the
inverse of the status of CIO 000003. To arrive at the execution condition for the
instruction at the right, the logical AND of the execution conditions resulting from
these two blocks would have to be taken. AND LOAD does this. The mnemonic
code for the ladder diagram is shown to the right of the diagram. The AND LOAD
instruction requires no operands of its own, because it operates on previously
determined execution conditions. Here too, dashes are used to indicate that no
operands needs designated or input.
Address Instruction
Instruction
00000 LD
00001 OR
00002 LD
00003 OR NOT
00004 AND LD
Section 4-4
Operands
000000
000001
000002
000003
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