0
1
2
3
4
5
6
7
10
11
12
13
14
15
16
17
20
143
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
99
00
01
02
03
04
05
06
07
08
09
0A
0B
0C
0D
0E
0F
10
63
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 1
0 1 1 0
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
0 1 1 1
1 0 0 0
1 0 0 1
1 0 1 0
1 0 1 1
1 1 0 0
1 1 0 1
1 1 1 0
1 1 1 1
0 0 0 0
0 0 1 1
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
1 0 0 1
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
0 1 1 1
1 0 0 0
1 0 0 1
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
1 0 0 1
..........
..........
..........
..........
..........
(2) Octal Number (OCT)
40
The assigned numbers of PLC’s external input and output terminals are displayed by the octal system.
For example,
The external input ports: X0 ~ X7, X10 ~ X17
The external output ports: Y0 ~ Y7, Y10 ~ Y17
(3) Decimal Number (DEC)
Decimal Number is the value system which people are familiar with. In PLC, a decimal number is always headed
with a “K” in front of the value. For example, K123 indicates a decimal number where the value is 123.
Application occasions of Decimal Number:
Used as the set value of the T and C, for example, K10
Used as the component number of the M, S, T or C, for example, M9, S10, etc.
Used as an Operand device in the applied instruction, for example, MOV K1 D1.
BCD is to express a Decimal digit unit with a Nibble or 4 bits. Sequential 16 bits can express 4 Decimal digits. BCD
is mainly used to read the input value of the Digital Switch (Thumbwheel input) or export the data to the
7-Segment Displayer for displaying the value.
(4) Binary Code Decimal (BCD)
In PLC, a Hex number is always headed with an “H”, for example, H123 represents a Hex number and is valued 123.
(5) Hexadecimal Number (HEX)
(6) Bits of the numerical system and the numerical conversion table:
OCT DEC HEX BIN
BCD