The PC GUI (see the C:\ti\mspm0_sdk_2_03_00_07\tools\metrology_gui directory in MSPM0 SDK) is used for viewing results and for calibrating the energy metrology function. During calibration, parameters called calibration factors are modified in the test software to give the least error in the energy measurement.

For this meter, there are six main calibration factors for each phase: voltage scaling factor, active power offset (erroneously called voltage AC offset in the GUI), current scaling factor, reactive power offset (erroneously called current AC offset in the GUI), power scaling factor, and the phase compensation factor. The voltage, current, and power scaling factors translate measured quantities in metrology software to real-world values represented in volts, amps, and watts, respectively. The power offset is used to subtract voltage to current crosstalk, which appears as a constant power offset and causes greater inaccuracies at lower currents. The last calibration factor is the phase compensation factor, which is used to compensate any phase shifts introduced by the current sensors and other passives.

The voltage, current, and power calibration factors are independent of each other. Therefore, calibrating voltage does not affect the readings for RMS current or power. When the Energy Metrology middleware is flashed on the MSPM0+ MCU for the first time, default initial values are loaded into these calibration factors. These default values are modified through the GUI during calibration. The calibration factors are stored into a FLASH sector in the MCU; and therefore, remains the same if the hardware is restarted. Calibrating any of the scaling factors is referred to as gain correction. Calibrating the phase compensation factors is referred to as phase correction. For the entire calibration process, the AC test source must be ON and the energy pulses connected to the reference meter.