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blocks a and b would be combined using AND LOAD as shown above, and
then block c would be coded and a second AND LOAD would be used to
combined it with the execution condition from the first AND LOAD. Then
block d would be coded, a third AND LOAD would be used to combine the
execution condition from block d with the execution condition from the sec-
ond AND LOAD, and so on through to block n.
Block
a
Block
b
00500
Block
n
Block
c
The following diagram requires an OR LOAD followed by an AND LOAD to
code the top of the three blocks, and then two more OR LOADs to complete
the mnemonic code.
00002 00003
LR 0000
00000
00001
00004 00005
00006 00007
Address Instruction Operands
00000 LD 00000
00001 LD 00001
00002 LD 00002
00003 AND NOT 00003
00004 OR LD --
00005 AND LD --
00006 LD NOT 00004
00007 AND 00005
00008 OR LD --
00009 LD NOT 00006
00010 AND 00007
00011 OR LD --
00012 OUT LR 0000
Although the program will execute as written, this diagram could be drawn as
shown below to eliminate the need for the first OR LOAD and the AND
LOAD, simplifying the program and saving memory space.
00002 00003
LR 0000
00001
00000
00004 00005
00006 00007
Address Instruction Operands
00000 LD 00002
00001 AND NOT 00003
00002 OR 00001
00003 AND 00000
00004 LD NOT 00004
00005 AND 00005
00006 OR LD --
00007 LD NOT 00006
00008 AND 00007
00009 OR LD --
00010 OUT LR 0000
The following diagram requires five blocks, which here are coded in order
before using OR LOAD and AND LOAD to combine them starting from the
Basic Ladder Diagrams Section 4-3
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