Compression configuration

When the observer for PI Data Archive creates a PI point, compression-related point attributes are not set. Therefore, PI Data Archive assigns default values to the compression attributes: Compressing, CompDev, CompMin, CompMax. See the PI Data Archive System Management Guide for information about these point attributes.

As installed, the PI Data Archive default point attributes enable compression. However, the default compression deviation probably is unsuitable for all PI points that the observer creates.

Note: Significant changes may not be archived for measurements that have a smaller range of values than the default compression deviation.

PI System Management Tools (PI SMT) can display the default attribute values but cannot change the system-wide defaults. To see the current default attribute values in PI Data Archive, follow these steps:

1. In PI SMT, select a PI Data Archive in the Collectives and Servers pane.

2. In the System Management pane, expand Points and select Point Classes.

3. In the main pane, select base. The default attributes for the Base class display.

4. However, PI SMT can change compression attribute values for individual PI points using the Point Builder.