MSP430F6779A: ACT/REACT and IR Pulse IN/OUT

Hi Brian,

Thanks again for posting the questions here on E2E.

Brian Antheunisse said:

1. Are the ACT and REACT GPIO outputs the PULSE 1 and PULSE2 needed for measurement and calibration?

For an energy meter application, we use the ACT output pulses to achieve more accurate results during calibration. Why? Well, there's a time element to the energy calculation versus the power calculation, so the pulses are an indication of power over time. Our accurate test source measures these pulses (which typically have units of pulse count per kWH consumed) coming back from the MSP430-based meter and compares the count with how much energy it's providing. Then, it calculates an error percentage. Using the EMDC GUI, there's a box where you can enter this error value to calibrate the Gain and Phase using the energy measurement values. Keep in mind that revenue-grade meters must be as accurate as possible, so you may not need this level of accuracy. As a side note, you can also use the Reactive pulses to measure its accuracy too although this isn't done often.

For calibrating according to power instead of energy, you're just concerned about tuning the power magnitude and wouldn't need to use the pulses. If you follow this approach, then your energy measurement will be slightly less accurate since the time-element wasn't accounted for. If I remember correctly, the energy value varies less than 0.5% between these methods.

Brian Antheunisse said:

2. What is IR Pulse IN/OUT used for. Necessary? (We did not implement)

I suspect this question is about the IR interface on the EVM. It's either an inherently isolated communication channel (IrDA?) or used to isolate the energy pulses from the meter to the pulse reader. If you provide more context to the question, I can try to give more details here. I doubt that you need it, but I could be wrong!

Regards,

James