I'm trying to figure out where these temp spikes are coming from? Temperature is sampled once a minute. As I hover the cursor on the graph, I can get the temp in the bubble for each minute on either side of the spike that is valid. The spike may appear between 4:05 AM and 4:06 AM. There are valid temperatures for both times with the spike appearing between them. The bubble doesn't jump to the top of the spike. [temp_spikes]

As I'm currently playing about with the chart node, I'll try to help - although I haven't seen anything similar in my temperature readings. From my experience, I would think that the spikes are actual data values being sent from your sensor, or created in the processing before the chart node. Can you tell us what kind of sensor you're using, and what nodes the data passes through before the chart? Probably the simplest way to check on what's happening is to add debug nodes on the output of each node in the chain, and have a look at the values related to the "spike".

The sensor is a ds18b20 into a RPi using the sensor ds18b20 node. I couldn't understand how the spike was appearing between read times?

What is the peak value? If it is 85 degrees then it shows power-on reset value. Google it to find why it may happen. There may be many reasons. (Wiring, device power supply ...)

A power-on reset is a thought. I have set up a debug node and will watch those values. I just thought it odd that hovering over the graph would not display the time stamp for those spikes.

Do you have a 4.7k pullup resistor between the data and positive rail on the DS18B20?

If they really are just the 85 deg thing those devices are known to do - you could just filter them out - either with a switch node (if a strict comparison) or the rbe node set to ignore changes greater than...

And this of course: [image] Counterfeit DS18B20 Hardware I just found this in another forum: [edit] This link https://www.maximintegrated.com/en/support/faqs/ds18b20-faq.html also shows that the real DS18B20 is also a lot more accurate than we think!

The graph hover-y thing isn't very accurate if you have a lot of points, and skips some of them as you move it. My own room temperature module updates every 10 minutes, and it's almost impossible to accurately position over any particular point on the graph - I'm recording daily min & max separately to get round it.

Well you don't need to do much more than identify that peak value is 85. For that even keep debugging or store chart output to file and examine file by hand. If it is power-on reset issue then make decision to even do something with hardware or adjust your flow to ignore such peaks. Or just accept those peaks as you know the reason.

Yes I do have a 4.7K. This application is for my horse water tank to monitor temp and turn a 1500 watt heater on and off. Instead of relying on the internal thermostat in the heater that keeps the water much above freezing. This is the third year of use and just starting seeing these spikes. I'll drop a node in the flow that will ignore these spikes and all should be good.

Node-RED

Node-RED Forum

Spikes On Temperature Graph

Dashboard

ghayne 29 November 2019 17:23 8

And this of course:

Topic		Replies	Views
Chart only showing recent data, not specified timeline General	24	489	7 December 2023
Temperature controls cooling control and a separate control for heating General node-red-dashboard	35	1658	21 March 2022
Two ds18b20 sensors and i get one temperature General	28	2063	2 September 2019
Dashboard chart will only display last few minutes Dashboard	24	6163	16 April 2019
Temperature sensor functionality General	6	511	30 November 2022

Copyright OpenJS Foundation and Node-RED contributors. All rights reserved. The OpenJS Foundation has registered trademarks and uses trademarks. For a list of trademarks of the OpenJS Foundation, please see our Trademark Policy and Trademark List. Trademarks and logos not indicated on the list of OpenJS Foundation trademarks are trademarks™ or registered® trademarks of their respective holders. Use of them does not imply any affiliation with or endorsement by them.

Spikes On Temperature Graph

Related topics