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Section Basic Ladder Diagrams 6-3 The first of each pair of conditions is converted to LOAD with the assigned bit operand and then ANDed with the other condition. The first two blocks can be coded first, followed by OR LOAD, the last block, and another OR LOAD, or the three blocks can be coded first followed by two OR LOADs. The mnemonic code for both methods is shown below. Address Instruction 00000 00001 00002 00003 00004 00005 00006 00007 00008 LD AND NOT LD NOT AND NOT OR LD LD AND OR LD OUT Operands 00000 00001 00002 00003 — 00004 00005 — 20001 Address Instruction 00000 00001 00002 00003 00004 00005 00006 00007 00008 LD AND NOT LD NOT AND NOT LD AND OR LD OR LD OUT Operands 00000 00001 00002 00003 00004 00005 — — 20001 Again, with the method on the right, a maximum of eight blocks can be combined. There is no limit to the number of blocks that can be combined with the first method. Combining AND LOAD and OR LOAD Both of the coding methods described above can also be used when using AND LOAD and OR LOAD, as long as the number of blocks being combined does not exceed eight. The following diagram contains only two logic blocks as shown. It is not necessary to further separate block b components, because it can coded directly using only AND and OR. 00000 00001 00002 00003 20001 00201 00004 Block a Block b Address Instruction 00000 00001 00002 00003 00004 00005 00006 00007 LD AND NOT LD AND OR OR AND LD OUT Operands 00000 00001 00002 00003 00201 00004 — 20001 Although the following diagram is similar to the one above, block b in the diagram below cannot be coded without separating it into two blocks combined with OR LOAD. In this example, the three blocks have been coded first and then OR LOAD has been used to combine the last two blocks followed by AND LOAD to combine the execution condition produced by the OR LOAD with the execution condition of block a. 344
