Storage Method

You can select the storage method to use for trend tags and SPC tags. You are given a choice of either Scaled or Floating Point. Scaled represents a 2-byte data storage method; floating point uses 8 bytes.

Floating point storage has a dramatically expanded data range in comparison to scaled storage, allowing values to be more precise, but it also uses more disk space. Use scaled where compatibility with pre-V5.31 trend history files is necessary.

You can set the necessary storage method via the Trend Tag or SPC Tag properties. The storage method is set to Scaled by default.

Note:
• Trend records need to explicitly define their trend storage method. The compiler will raise an error if not defined. In previous versions, the default when not defined was "Scaled (2 byte)"8 byte. When upgrading, customers should set the trend storage method for blank entries to match the default from the previous version.
• If you edit this property in an existing project, you need to delete the associated trend files before you run the new runtime system. (For location of the trend files, see the File Name property for the trend tag.)

See Also

Calculate Disk Storage