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structions require no operands, while others require up to three operands,
Program Memory addresses can be from one to four words long.
Program Memory addresses start at 00000 and run until the capacity of Pro-
gram Memory has been exhausted. The first word at each address defines
the instruction. Any definers used by the instruction are also contained in the
first word. Also, if an instruction requires only a single bit operand (with no
definer), the bit operand is also programmed on the same line as the instruc-
tion. The rest of the words required by an instruction contain the operands
that specify what data is to be used. When converting to mnemonic code, all
but ladder diagram instructions are written in the same form, one word to a
line, just as they appear in the ladder diagram symbols. An example of mne-
monic code is shown below. The instructions used in it are described later in
the manual.
Address Instruction Operands
00000 LD HR 0001
00001 AND 00001
00002 OR 00002
00003 LD NOT 00100
00004 AND 00101
00005 AND LD 00102
00006 MOV(21)
000
DM 0000
00007 CMP(20)
DM 0000
HR 00
00008 LD 25505
00009 OUT 00501
00010 MOV(21)
DM 0000
DM 0500
00011 DIFU(13) 00502
00012 AND 00005
00013 OUT 00503
The address and instruction columns of the mnemonic code table are filled in
for the instruction word only. For all other lines, the left two columns are left
blank. If the instruction requires no definer or bit operand, the operand col-
umn is left blank for first line. It is a good idea to cross through any blank
data column spaces (for all instruction words that do not require data) so that
the data column can be quickly scanned to see if any addresses have been
left out.
When programming, addresses are automatically displayed and do not have
to be input unless for some reason a different location is desired for the in-
struction. When converting to mnemonic code, it is best to start at Program
Memory address 00000 unless there is a specific reason for starting else-
where.
4-3-3 Ladder Instructions
The ladder instructions are those instructions that correspond to the condi-
tions on the ladder diagram. Ladder instructions, either independently or in
combination with the logic block instructions described next, form the execu-
tion conditions upon which the execution of all other instructions are based.
The first condition that starts any logic block within a ladder diagram corre-
sponds to a LOAD or LOAD NOT instruction. Each of these instruction re-
LOAD and LOAD NOT
Basic Ladder Diagrams Section 4-3
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