parasite power
Posted: 29 Dec 2023, 15:12
I have 4 ds18b20 temp sensors connected to GPIO13 on a D1 Mini ESP8266. They are the sealed variety with what appears to be a stainless steel end. 3 of the sensors in their Device menu are returning that they are parasite powered and one is not showing to be parasite powered. They are not wired up to be parasite powered. Two sensors are on a somewhat longer run of about 6 feet of cable and the other two are just the standard foot or whatever they come in. I started noticing some dropped readings occasionally so I looked into it and the parasite powered status on the menu caught my eye. Does this mean I have a sensor that is shorted over to ground or a bad sensor or something? Any advice on how I troubleshoot this situation? How does it know, or how does it determine it is parasite powered? Why would 3 of the 4 report that and not all of them when they are all tied on the same one wire line? I would think if its a wiring or sensor issue, it would tag them all as parasite powered. BUT, I dont understand those inner workings enough to know. Do the microcontrollers detect this parasite power or is this specific to espeasy? I really couldnt tell from the docs.
I spent some time putting it into a water proof enclosure and installing it all nice & its mounted outside. I am fairly sure nothing is wet, it just reads temps inside the enclosure, outside the enclosure, inside my well house temp and water line temp. Then enclosure is mounted on the outside so that I get good wifi connection without being blocked from the well house. But if that reporting that its parasite powered is an indicator of a bad sensor or wiring issue thats where I will start.
I have tried it with the latest normal firmware, latest climate firmware, and I reverted back to normal 20230930. It seemed like the latest firmwares had a very sluggish gui, like it was struggling with the wifi connection. Which was odd because I never lost connection and the mqtt messages kept rolling fine. But I didnt spend much time playing with it because I feel i need to get this parasite power thing addressed first and I dont feel I know enough about how to diagnose it. Is there some logs that I can watch or something first or do I just need to start disconnecting sensors?
I should add that the sensors all do report what seems to be valid accurate readings all around the clock. I may get 3 readings in a 12 hour period that are errors or it couldnt read or whatever. And it seems to be on all sensors about the same times. All sensors are on 12 resolution. I have been filtering out the bad readings by setting the error state value to 125 and the mqtt message to node red I just disregarding any reading over 120.
Rob
I spent some time putting it into a water proof enclosure and installing it all nice & its mounted outside. I am fairly sure nothing is wet, it just reads temps inside the enclosure, outside the enclosure, inside my well house temp and water line temp. Then enclosure is mounted on the outside so that I get good wifi connection without being blocked from the well house. But if that reporting that its parasite powered is an indicator of a bad sensor or wiring issue thats where I will start.
I have tried it with the latest normal firmware, latest climate firmware, and I reverted back to normal 20230930. It seemed like the latest firmwares had a very sluggish gui, like it was struggling with the wifi connection. Which was odd because I never lost connection and the mqtt messages kept rolling fine. But I didnt spend much time playing with it because I feel i need to get this parasite power thing addressed first and I dont feel I know enough about how to diagnose it. Is there some logs that I can watch or something first or do I just need to start disconnecting sensors?
I should add that the sensors all do report what seems to be valid accurate readings all around the clock. I may get 3 readings in a 12 hour period that are errors or it couldnt read or whatever. And it seems to be on all sensors about the same times. All sensors are on 12 resolution. I have been filtering out the bad readings by setting the error state value to 125 and the mqtt message to node red I just disregarding any reading over 120.
Rob