Omron SYSMAC C1000H, Operation Manual

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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 below. The AND LOAD in-
struction 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.
The following diagram requires an OR LOAD instruction between the top log-
ic block and the bottom logic block. An ON execution condition would be pro-
duced for the instruction at the right either when IR 00000 is ON and IR
00001 is OFF or when IR 00002 and IR 00003 are both ON. The operation of
and mnemonic code for the OR LOAD instruction is exactly the same as
those for a AND LOAD instruction except that the current execution condition
is ORed with the last unused execution condition.
Instruction
00000 00001
00002 00003
Address Instruction Operands
00000 LD 00000
00001 AND NOT 00001
00002 LD 00002
00003 AND 00003
00004 OR LD ---
Naturally, some diagrams will require both AND LOAD and OR LOAD instruc-
tions.
To code diagrams with logic block instructions in series, the diagram must be
divided into logic blocks. Each block is coded using a LOAD instruction to
code the first condition, and then AND LOAD or OR LOAD is used to logically
combine the blocks. With both AND LOAD and OR LOAD there are two ways
to achieve this. One is to code the logic block instruction after the first two
blocks and then after each additional block. The other is to code all of the
blocks to be combined, starting each block with LOAD or LOAD NOT, and
then to code the logic block instructions which combine them. In this case,
the instructions for the last pair of blocks should be combined first, and then
each preceding block should be combined, working progressively back to the
first block. Although either of these methods will produce exactly the same
result, the second method, that of coding all logic block instructions together,
can be used only if eight or fewer blocks are being combined, i.e., if seven or
fewer logic block instructions are required.
OR LOAD
Logic Block Instructions in
Series
Basic Ladder Diagrams
Section 4-3