Hello,
I recently setup my NodeMCU with 2 x DS18b20 units based on this wiki page: https://www.letscontrolit.com/wiki/inde ... alibrating
The 2 x DS18b20 were connected (as per the wiki page) via a short Cat5e cable utilising RJ45 sockets, then each of the DS18b20 had an RJ45 plug attached to the end of the cable that came with the DS18b20 (the cable is approx 40cm long). On the prototype breadboard I used a 47K ohm pullup resistor. Everything worked as expected and I had the following on the Devices screen.
I then ran a Cat5e cable approx 5 meters to the location where I wanted one of the DS18b20 to be located. After plugging everything in I found this on the Devices screen.
Here's what Temp2 looked like in the devices screen... note the address of the DS18b20 is gone?
I then unplugged the 'local' DS18b20 and left the DS18b20 connected to the 5 meter cable, the DS18b20 at the end of the 5 meter cable was working and providing temperature readings. I plugged back in the local DS18b20 and everything stopped working again??
The power to the 2 x DS18b20 is setup as per the wiki page above.
I am sure the issue is a simple one... but after reading mutiple forum pages I am no closer to a solution. I suspect it is a 'power' problem... So do I change the power supply (I am using a USB style 800ma plug pack power supply connected to the NodeMCU), or connect directly to the DS18b20? Do I change the pullup resistor?
Advice appreciated?
Thanks, Mark
DS18b20 Weird Behaviour
Moderators: grovkillen, Stuntteam, TD-er
Re: DS18b20 Weird Behaviour
As an update... I have noticed intermittent times when the Temp2 sensor is not contactable. Here's the log screen:-
Thanks, Mark
Thanks, Mark
Re: DS18b20 Weird Behaviour
Ended up completely rewiring based on feedback from Grovkillen, changing the pullup resistor, and the issue appears to have disappeared. I suspect the root cause was operator error
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