Ranges of ExcMax and CompMax

The PI API protocol defines the ExcMax and CompMax attributes as a signed 16-bit integer. If Data Archive stores a value that is larger than 32,767, the value returned by the PI API is 32,767.

Interfaces use exception max to ensure that they are sending data between exception min and exception max; the values of exception min and max are held in an int 16 variable, meaning the values can be between -32767 and 32767. It's important to note that interfaces do NOT have to obey these parameters. In special cases, interfaces which have data greater than 32767, or less than -32767, can choose not to obey these parameters. It's up to the interface and interface programmer.

Compression is controlled on the Data Archive side. The compression value (32 bit), once configured on the Data Archive node, will only take effect on the server node itself.

The values of these point attributes are stored as unsigned 32-bit integers. The maximum value of each is 4,294,967,295 seconds.

PI SDK applications obtain from the Data Archive signed 32-bit integer values for ExcMax and CompMax.

Note: For more information, see ExcDev, ExcDevPercent, ExcMax, and ExcMin.