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Number Systems
The following example illustrates why it is so easy to convert binary values hexadecimal
values:
1
1
15
F
*
Converting the 4-bit blocks to decimal values does not directly produce a value that corresponds to the complete
16-bit binary value! In contrast, the binary value can be converted directly to hexadecimal notation with exactly the
same value as the binary value.
Octal numbers
Inputs X8 and X9 and outputs Y8 and Y9 do not exist on the base units of the MELSEC FX fam-
ily. This is because the inputs and outputs of MELSEC PLCs are numbered using the octal
number system, in which the digits 8 and 9 don't exist. Here, the current digit is reset to 0 and
the digit in the next position is incremented after the count reaches 7 (0 – 7, 10 – 17, 70 – 77,
100 – 107 etc).
–
Base: 8
–
Digits: 0, 1, 2, 3, 4, 5, 6, 7
Summary
The following table provides an overview of the four different number systems:
Decimal notation
3 – 4
1
1
0
1
1
0
5
5
Octal notation
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
:
99
:
1
0
1
1
1
0
11
B
Hexadecimal notation
0
1
2
3
4
5
6
7
10
11
12
13
14
15
16
17
20
:
143
:
An Introduction to Programming
0
1
Binary
9
Decimal*
9
Hexadecimal
Binary notation
0
0000 0000 0000 0000
1
0000 0000 0000 0001
2
0000 0000 0000 0010
3
0000 0000 0000 0011
4
0000 0000 0000 0100
5
0000 0000 0000 0101
6
0000 0000 0000 0110
7
0000 0000 0000 0111
8
0000 0000 0000 1000
9
0000 0000 0000 1001
A
0000 0000 0000 1010
B
0000 0000 0000 1011
C
0000 0000 0000 1100
D
0000 0000 0000 1101
E
0000 0000 0000 1110
F
0000 0000 0000 1111
10
0000 0000 0001 0000
:
63
0000 0000 0110 0011
:
MITSUBISHI ELECTRIC
:
:
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