Mitsubishi Electronics FX1S manual Floating Point And Scientific Notation, Some useful constants

FX Series Programmable Controllers Devices in Detail 4

4.15Floating Point And Scientific Notation

FX1S

FX1N

FX2N FX2NC

PLC’s can use many different systems and methods to store data.

The most common have already been discussed in previous sections e.g. BCD, Binary, Decimal, Hex. These are what is known as ‘integer’ formats or ‘whole number formats’.

As the titles suggest these formats use only whole numbers with no representation of fractional parts. However, there are two further formats which are becoming increasingly important and they are:

a)Floating point and

b)Scientific notation

Both of these formats are in fact closely related. They both lend themselves to creating very large or very small numbers which can describe both whole and fractional components.

General note:

• Sometimes the words ‘Format’, ‘Mode’ and ‘Notation’ are interchanged when descrip- tions of these numerical processes are made. However, all of these words are providing the same descriptive value and as such users should be aware of their existence.

Some useful constants

π	3.141	✕ 100
2π	6.283	✕ 100
π/4	7.853	✕ 10-1
π2	9.869	✕ 100
The speed of light	2.997	✕ 108 m/s
Gravity, g	9.807	✕ 100 m/s2
e	2.718	✕ 100

Fixed points:
Boiling point of liquid oxygen	-1.8297 ✕ 102 °C
Melting point of ice	0.00	✕ 100		°C
Triple point of water	1.00	✕	10-2°C
Boiling point of water	1.00	✕	102	°C

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