FactoryTalk View: Graphics Support Single Precision Floating Point Values

Refer to Tech Note 55300.

Applicable for both FactoryTalk View Machine Edition (ME) and FactoryTalk View Site Edition (SE).

In computing, real numbers can be represented by single precision or double precision floating point values. The IEEE 754 Standard defines a single precision floating point as a representation of a real number using 4 bytes of computer memory which can provide for a significant precision of 24 bits (or maximum 7 significant digits) whereas a double precision floating point uses 8 bytes of computer memory which can provide a significant precision of 53 bits (or maximum 15 significant digits).

FactoryTalk View SE Graphics supports single precision floating point values, and by default only provides for 6 significant digit accuracy. 

Note: digits displayed before the decimal point count as part of the total significant digits. 

Any digits displayed after the 6 significant digit are approximations only and should not be treated as significant. This limitation can result in unexpected behavior. FactoryTalk View SE utilizes the Numeric Display and Numeric Input objects to display and input tag values. To display floating point values, the Format and Decimal Places properties for these objects must be reset to Floating Point and the desired number of decimals.

Note: Setting the number of decimal places does NOT specify the number of significant digits that will be displayed.

When a display is opened, both the Numeric Display and Numeric Input objects can display values that have more than 6 digits however only the first 6 digits will be significant (accurate).

If the Numeric Input object is used to write a value with more than 6 digits, the value displayed by the Numeric Input will differ from that displayed by a Numeric Display. In the Numeric Input object, all digits displayed after the 6 significant digit will be displayed as zeros (0) with the digit rounded up or down to its nearest value.

Examples (with Decimal Places set to 6): 

writing: 1.123456 will display: 1.123460

writing: 12.123456 will display: 12.123500

writing: 123.123456 will display: 123.123000