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- Device & model you are using (Ex: Pi 2 Model B or Arduino Uno with W5100 ethernet shield)
Pi3 Model B
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I have two DS18B20 sensors connected to the RPi. I have set triggers for one of the sensors to turn a heater on when temperature drops below 120F and shut it off when above 128F. It works fine generally. However, twice now the temperature ranges on the triggers have somehow reset themselves to 0-20F with the trigger set at the max of 20F. I actually have three triggers on this device and all end up showing 0-20F. I also have two other RPi devices in other applications with temperature-based triggers that have never demonstrated this behavior (one a pi2 and one a pi3). When I try to adjust the range and reset the trigger temperature on the troublesome unit it will not stick. Goes right back to 0-20 when I go back into the trigger after editing it. The only way that I have found to correct it is to delete the trigger and recreate it. Any suggestions?
Hey @burnham,
We’re aware of a bug where the min/max range for DS18B20 triggers resets to it’s ‘default’ values after saving and re-entering a trigger. This is easily reproduced with any DS18B20 by doing something like setting the range from 0 to 500, saving, then re-opening the trigger. The issue where I’m currently stumped is that that default range should be -67F to 257F, the operating range of that sensor.
In your case, somehow the UI has decided that the range is 0 to 20F so its reverting to that, which actually moves the trigger value because it has to be contained in the range. We’ve seen one other case of it in the forums in this thread: DS18B20 Temperature Trigger Slider - #7 by rsiegel
In that guy’s case the UI is limited to an even more restricting 71F-72.5F.
Ultimately we just need to fix the bug to retain user defined ranges then this shouldn’t be an issue anymore. Until then, I’d be interested if you could try the steps listed in that post I linked above (making the same assumptions about your wiring that I did for him there, too). Basically for each DS18B20 where the trigger range is anything but -67F to 257F, delete the actual DS18B20 widget itself (and any associated triggers), then reboot the pi and let Cayenne auto-create new DS18B20 widgets for you when it detects the sensors on the 1-Wire bus (GPIO 4)
Also tagging @wbarsuhn in case you’re still around, I’m curious if the steps in that linked thread (your thread) worked for you or not.
I deleted the two ds18b20 sensors. Cayenne then auto-created new ones before I had a chance to reboot. Rebooted anyway. So then I created all new triggers for the set-points that I wanted. The ranges for the sensors were both shown to be -66F to 257F. So all is good for now. I will report back if they go back to something other than the default.
Thanks for the update. I’m glad that it’s working with the updated changes – I do have some concern it could re-occur since while we know the symptoms, we haven’t nailed down exactly what caused it.
As I see it we have two closely related issues to monitor
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That the min/max ranges aren’t retained when you view the trigger after clicking ‘save’. We understand this one well and just need to get a fix for it.
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That there is some scenario for which the default min/max ranges are being changed (basically however your widget decided that its range was 0F-20F). Maybe it won’t be much of an issue with #1 fixed, but I’ll be on the lookout for it.
That’s for us to worry about internally. 
I do appreciate your offer to let us know if it re-occurs, of course.
