5
Binary, decimal and hexadecimal code
Before going into the Hitachi PLC details, it is important to understand the numbering system of the
PLC. Electric devices like PLC’s can handle only digital data. The minimum unit of digital data is a
“bit”. 1 bit has two states, 0 or 1.
4 bits can give us 16 different values because of 2
4
as below left.
Since 4 bits of data is not easy to handle, the data is translated to hexadecimal code 0 to F as above
right. One hexadecimal code (= 4 bits) can express 16 different values.
4 hexadecimal codes have 65,535 values (= 16
4
). This unit (4 hexadecimal codes = 16 bits) is called
as “Word”. Normally Hitachi PLC handles binary data and word data.
This is a comparison table of one “Word” in binary, decimal and hexadecimal expressions.
2 10 16 2 10 16
0000 0000 0000 0000 0 H 0000 0000 0000 0011 1111 63 H 003F
0000 0000 0000 0001 1 H 0001 0000 0000 0100 0000 64 H 0040
0000 0000 0000 0010 2 H 0002
0000 0000 0000 0011 3 H 0003 0000 0000 1111 1111 255 H 00FF
0000 0000 0000 0100 4 H 0004 0000 0001 0000 0000 256 H 0100
0000 0000 0000 0101 5 H 0005
0000 0000 0000 0110 6 H 0006 0000 0011 1111 1111 1023 H 03FF
0000 0000 0000 0111 7 H 0007 0000 0100 0000 0000 1024 H 0400
0000 0000 0000 1000 8 H 0008
0000 0000 0000 1001 9 H 0009 0000 0111 1111 1111 2047 H 07FF
0000 0000 0000 1010 10 H 000A 0000 1000 0000 0000 2048 H 0800
0000 0000 0000 1011 11 H 000B
0000 0000 0000 1100 12 H 000C 0000 1111 1111 1111 4095 H 0FFF
0000 0000 0000 1101 13 H 000D 0001 0000 0000 0000 4096 H 1000
0000 0000 0000 1110 14 H 000E
0000 0000 0000 1111 15 H 000F 0111 1111 1111 1111 32767 H 7FFF
0000 0000 0001 0000 16 H 0010 1000 0000 0000 0000 32768 H 8000
0000 0000 0001 1111 31 H 001F 1111 1111 1111 1111 65535 H FFFF
0000 0000 0010 0000 32 H 0020
4 bits
16 values
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