AC voltage measurement

How fast NodeRed receives and plot data? I saw some suggestions about what I’m intending to do, however none has pointed to this question.

I’ve been working and learning NodeRed for quite some time now. I’m basically using it for everything. However, it’s quite difficult to determine its limitations since I never push it.

I want to plot AC voltage and current. Not RMS values, but the whole sine wave.

We have this teaching lab where students play with electric motors. From time to time they broke probes, scope and so on. I just want to use cheap electronics to read AC voltage and current. My only question is: which is the best way to plot it?

I will just readAdc and write over serial.
I can’t imagine what will happen if I just push it to nodered.

I will, probably, need to build a buffer to be able to see something static, but I’m not sure about feasibility.

If you want to capture and display real time waveforms at 50 or 60 Hz node-red is not the best candidate as it is single-threaded. You didn't say what hardware you are using.

Probably an ESP32. To get what I want with NodeRed I will need to send an array to char and show each second, for instance?

@ghayne Do you have other suggestion?

I have been trying to push data to an InfluxDB database at 20Hz on a raspberry Pi 3B+ with no luck. Too many processes interrupting the flow. Also the ESP32 has terrible interrupt latency as things Like Arduino or Micropython run on top of the RTOS OS.

An esp + web sockets + JavaScript can do amazing things even when it comes to fast data transfer:

You can find more amazing stuff on CNLohrs channel!

And if your students do something wrong the probably only break only a 2€/$ wemos not a raspberry pc or your scope.


This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.