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Basic Ladder Diagrams Section 4-3
Again, this diagram can be redrawn as follows to simplify program structure
and coding and to save memory space.
The next and final example may at first appear very complicated but can be
coded using only two logic block instructions. The diagram appears as follows:
The first logic block instruction is used to combine the execution conditions
resulting from blocks a and b, and the second one is to combine the execution
condition of block c with the execution condition resulting from the normally
closed condition assigned IR 00003. The rest of the diagram can be coded
with OR, AND, and AND NOT instructions. The logical flow for this and the
resulting code are shown below.
00006 00007
LR 0000
00005
00001 00002
00003 00004 00000
Address Instruction Operands
00000 LD 00006
00001 AND 00007
00002 OR 00005
00003 AND 00003
00004 AND 00004
00005 LD 00001
00006 AND 00002
00007 OR LD --
00008 AND 00000
00009 OUT LR 0000
00000 00001
10000
00002 00003
01000 01001
00004 00005
10000
00006
Block cBlock b
Block a
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