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Data Formats
0000
00
0000
0002
01
07
0000
0002
01
07
0000
00
4-11 Program Execution
4-12 Data Formats
4-12-1 Unsigned Binary Data
Bit
15
14
15
14
2
2
↓
↓
3
2
2
2
3
Digit
16
90
When drawing ladder diagrams, it is important to keep in mind the number of
instructions that will be required to input it. In diagram A, below, an OR LOAD
instruction will be required to combine the top and bottom instruction lines. This
can be avoided by redrawing as shown in diagram B so that no AND LOAD or OR
LOAD instructions are required. Refer to 5-6-5 AND LOAD and OR LOAD for
more details and 4-4-1 Logic Block Instructions for further examples of diagrams
requiring AND LOAD and OR LOAD.
Diagram A
Diagram B
When execution or a ladder diagram is started, the CPU scans the program from
top to bottom, checking all conditions and executing all instructions accordingly
as it moves down the bus bar. It is important that instructions be placed in the
proper order so that, for example, the desired data is moved to a word before that
word is used as the operand for an instruction. Remember that an instruction line
is completed to the terminal instruction at the right before executing instruction
lines branching from the first instruction line to other terminal instructions at the
right.
Program execution is only one of the tasks carried out by the CPU as part of the
cycle time. Refer to Section 6 Program Execution Timing for details.
The following data formats can be handled by the various calculation and con-
version instructions.
• Unsigned binary
• Signed binary
• Unsigned BCD
• Signed BCD
• Floating-point
Data is configured in words, with 16 bits per word. This data is regarded as 16-bit
binary data. Unsigned binary data is often written as four-digit hexadecimal
(0000 to FFFF).
13
12
11
10
13
12
11
10
2
2
2
2
↓
↓
↓
↓
1
0
3
2
2
2
2
2
2
16
0002
Address
07
00000
00001
00002
00003
00004
0002
07
Address
00000
00001
00002
00003
09
08
07
06
9
8
7
6
2
2
2
2
↓
↓
↓
↓
1
0
3
2
2
2
2
2
1
16
Section 4-12
Instruction
Operands
LD
000000
LD
000001
AND
000207
OR LD
---
OUT
000207
Instruction
Operands
LD
000001
AND
000207
OR
000000
OUT
000207
05
04
03
02
5
4
3
2
2
2
2
2
↓
↓
↓
↓
1
0
3
2
2
2
2
2
0
16
01
00
1
0
2
2
↓
↓
1
0
2
2
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