Voltage reporting different on iotawatt.local vs. EmonCMS for the same device


I deployed an IoTaWatt today at a client’s house specifically for voltage data-logging (we suspect high voltage is causing a ductless mini-split heat pump to shut down) and am using Emoncms for remote reporting. While confirming I had everything set up correctly out on site, I noticed that the voltage reported at iotawatt.local was a few Volts higher than what shows up on the graph on Emoncms. What gives!?!

I double-checked that the IoTaWatt upload settings to Emoncms were correct.

One other note: ignore the very high voltage numbers in the (higher) IoTaWatt graph. A little while after taking those screenshots I calibrated the IoTaWatt voltage reporting (lower) to match a pair of quality RMS clamp ammeters I brought along. After that, the reporting on Emoncms was still a few Volts low.

These two do not appear to be graphs of the same dataset. The two should be just about exactly the same. Are you uploading to Emoncms.org? If so, are you sure you are looking at the correct node, or that there isn’t another unit uploading somewhere to the same node?

If you are using your own Emoncms, is it a RPi with its own voltage reference that is being plotted?

It should be data from the same device. I’m uploading to Emoncms.org, and am looking at the correct node. For this application, I used an IotaWatt that I had previously used at a different location…but from an Emoncms.org standpoint, it’s a new node. It has a new name and I’m only uploading the voltage data. I also renamed it locally.

If we can’t figure this out, it’s not the end of the world. I can still retrieve all the correct voltage data next time I visit that site in person.

I’m sure it has an explanation, but I’d need to investigate. Would need the IoTaWatt Emoncms uploader setup and see the Emoncms inputs setup to start.



Got it. I’m attaching a couple of screenshots from the Emoncms.org inputs setup.

It may be a moot point by the time I get back to the site to collect it (since I’ll then have access to the local/accurate data)…but will send screenshots of the Iotawatt Emoncms uploader setup at a later date. Thank you.

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