I’m in the USA, on 240V split-phase service, with two Iotawatts mounted in a box about 6 inches apart monitoring each circuit that I have individually. They share a common 5V USB power supply via a soldered splice, and they share a 9VAC transformer via a “y” cable.
I replaced one of the two Iotawatts hoping to solve this issue, but the new one is showing the same kind of behavior, so I’m guessing that there’s something about my setup that’s causing issues. And, like most flaky issues, there are lots of symptoms, most of which are probably red herrings.
So, what I’m seeing is that after running perfectly fine for “awhile” (several hours, but less than a day), the first of the two Iotawatts (let’s call them Iotawatt_A and Iotawatt_B)will stop responding when I try to communicate via a browser. So, some possibly red-herring symptoms:
- If I leave the browser open on one of the Iotawatt_A pages before it dies, I can navigate to some other pages (but not all). I think this is an artifact of the HTML and browser caching, though, and not the Iotawatt actually responding.
- If I try to create a new connection to Iotawatt_A, the browser doesn’t fail to connect to the Iotawatt - I just get a spinning wait indicator. Perhaps the Iotawatt is alive enough to create a TCP connection, but not alive enough to respond to the HTTP query?
- If I leave the browser open to the “Status” page, I can notice that the “AC Cycles sampled / sec” drops from it’s normal ~39 to 0.
3a. Playing with the 9VAC transformer recovers the unit when it’s in this mode. Disconnecting/reconnecting the 9V jack makes it happy, unplugging/plugging the Xfmr makes it happy, disconnecting/reconnecting the 9V jack on the OTHER iotawatt makes it happy.
3b. The Iotawatt will eventually become non-responsive again.
- If I leave the browser open to Graph+, I can see that the Iotawatt stops sampling - all of the graph lines go flat at their last valid values. (See attached; the graph shows the iotawatt stopped taking data about ~1:45 AM, and the log shows the iotawatt resetting 6:56 AM. The graph doesn’t show the Iotawatt taking data after 6:56, until I power-cycled at 8:28 AM). The other Iotawatt was happy during this period.
- This all worked fine a year ago when I originally installed, although there were occasional, similar hiccups with the old Iotawatt_A that got more frequent.
So, the question is, where’s the problem?
- The shared 5V supply might be a problem. How much current does the Iotawatt pull?
- The shared 9VAC might be a problem. If it fails, the “AC Cycles Sampled” goes to zero, which I can understand, but it shouldn’t cause the unit to become unresponsive. I’ve replaced the original Y cable I got from you with one I built, and the same problem occurs. Maybe I’ll gin up something that let’s me externally measure the 9VAC when the unit stops sampling.
- The units being physically close together might be a problem - EMI from one causing problems with the other, but this seems really unlikely to me.
- Any other thoughts?