1 OVERVIEW
1.2 Data Specification Method
49
1
Configuration of double-precision real number data
Double-precision real number data consists of a sign, mantissa, and exponent, and is expressed as shown below.
The following figure shows the bit configuration of the internal expression of double-precision real number data and the
meaning of each part.
■
Sign (1 bit)
This bit represents the positive or negative sign of a numerical value. "0" indicates a positive number or 0. "1" Indicates a
negative number.
■
Mantissa (52 bits)
A mantissa means XXXXX
of 1.XXXXX
2
N
representing a single-precision real number in binary.
■
Exponent (11 bits)
An exponent means N of 1.XXXXX
2
N
representing a single-precision real number in binary. The following table shows the
relationships between the exponent value and N of a single-precision real number.
Precautions
■
When setting an input value of single-precision real number from the engineering tool
The number of significant digits is about 7 because the engineering tool processes single precision real number data in 32-bit
single precision.
When the input value of single-precision real number data exceeds 7 digits, the 8th digit is rounded off.
Therefore, if the rounded-off value goes out of the range from -2147483648 to 2147483647, it will not be an intended value.
Ex.
When "2147483647" is set as an input value, it is handled as "2147484000" because 8th digit "6" is rounded off.
Ex.
When "E1.1754943562" is set as an input value, it is handled as "E1.175494" because 8th digit "3" is rounded off.
■
When setting an input value of double-precision real number from the engineering tool
The number of significant digits is about 15 because the engineering tool processes double precision real number data in 64-
bit double precision.
When the input value of double-precision real number data exceeds 15 digits, the 16th digit is rounded off.
Therefore, if the rounded-off value goes out of the range from -2147483648 to 2147483647, it will not be an intended value.
Ex.
When "2147483646.12345678" is set as an input value, it is handled as "2147483646.12346" because 16th digit "6" is
rounded off.
Ex.
When "E1.797693134307" is set as an input value, it is handled as "E1.7976931307" because 16th digit
"5" is rounded off.
Exponent (b52 to b62)
7FFH
7FEH
7FDH
401H
400H
3FFH
3FEH
02H
01H
00H
N
Not used
1023
1022
2
1
0
-1
-1021
-1022
Not used
1.
× 2
Mantissa
Sign
Exponent
b63
b62
∙∙∙
b52
b51
b16
∙∙∙
b15
b0
∙∙∙
Sign
Exponent
Mantissa
Summary of Contents for MELSEC iQ-R Series
Page 1: ...MELSEC iQ R Programming Manual Instructions Standard Functions Function Blocks ...
Page 2: ......
Page 24: ...22 INDEX 2092 INSTRUCTION INDEX 2093 REVISIONS 2104 WARRANTY 2105 TRADEMARKS 2106 ...
Page 34: ...32 MEMO ...
Page 35: ...33 PART 1 PART 1 OVERVIEW This part consists of the following chapter 1 OVERVIEW ...
Page 68: ...66 1 OVERVIEW 1 5 Precautions on Programming MEMO ...
Page 1448: ...1446 14 REDUNDANT SYSTEM INSTRUCTIONS 14 2 Disabling Enabling System Switching MEMO ...
Page 1972: ...1970 33 TIME DATA TYPE FUNCTIONS 33 4 Division MEMO ...
Page 2067: ...APPX Appendix 5 PID Control Program Examples 2065 A 252 Set PID control data for loop 2 ...
Page 2109: ......