Mitsubishi Electric MELSEC Q Series Programming Manual page 46

Precautions
Precautions when an input value of a single/double-precision real number is set using a programming tool are shown below.
■Single-precision real
Single-precision real data are processed as 32-bit single precision in the programming tool, and thus the number of significant
figures becomes approximately 7. If the input value of single-precision real data exceeds 7 digits, the 8th digit is rounded. If
the value after the rounding exceeds a value between -2147483648 and 2147483647, an operation error occurs.
Example 1: When '2147483647' is set for the input value
Example 2: When 'E1.1754943562' is set for the input value
■Double-precision real
Double-precision real data are processed as 64-bit double precision in the programming tool, and thus the number of
significant figures becomes approximately 15. If the input value of double-precision real data exceeds 15 digits, the 16th digit
is rounded. If the value after the rounding exceeds a value between -2147483648 and 2147483647, an operation error
occurs.
Example 1: When '2147483646.12345678' is set for the input value
Example 2: When 'E1.7976931348623157+307' is set for the input value
4 PROGRAM CONFIGURATION
44
4.4 Method for Specifying Data
8th digit '6' is rounded.
The value is handled as '2147484000'.
8th digit '3' is rounded.
The value is handled as 'E1.175494'.
16th digit '6' is rounded.
The value is handled as '2147483646.12346'.
16th digit '5' is rounded.
The value is handled as 'E1.79769313486232+307'.