Issue

A device communicates normally in PME, but when its values are accessed through OPC, the OPC tag displays a quality of “uncertainLastUsableValue.”

Product Line

Power Monitoring Expert 9.0

Power Monitoring Expert 2020

Power Monitoring Expert 2021

Power Monitoring Expert 2022

Power Monitoring Expert 2023

Power Monitoring Expert 2024

Environment

OPC
Custom Measurements
Modbus Device Importer (MDI)

Cause

The measurement being accessed through OPC is a custom measurement that PME has not yet registered in its internal mapping table (IAS_MeasurementAddress).
If PME does not have a measurement address entry, the OPC server cannot resolve it to a valid tag. When this occurs, the OPC server returns the quality “uncertainLastUsableValue,” indicating that PME has no current usable value associated with the tag.

Resolution

Force PME to create an internal mapping entry for the custom measurement by linking it to a Data Recorder.

To do this:

1. Open Designer.
2. Create a new Data Recorder.
3. Link one of the Data Recorder inputs to the custom measurement that does not appear correctly in OPC.
4. Link an External Pulse module to the trigger of the Data Recorder so that no actual logging occurs.

Once the custom measurement is mapped to a Data Recorder input, save and close Designer.
PME will then add an entry into IAS_MeasurementAddress, and the OPC server will return a valid quality for the tag.

Recommendation:

If you are using an older version of PME, consider upgrading to the latest version for improved protocol support and security. For assistance with integration or upgrades, contact Schneider Electric Technical Support at: pmo-psup@se.com