Hi, I have a load cell which a receive the value using MQQT (from my python script), then I would like to save the first 5 value coming from MQTT to compute the offset of my load cell. Then when I will have my offset, I can substract it from my msg.payload to set the load cell to 0. I have tried t…

Couple of things. You could use a for loop rather than while which would be easier to follow and also quicker. Secondly, you are just adding the current msg payload 5 times and then output it. I don't think that is what you meant? If you want to accumulate the last 5 messages from an MQTT topic, y…

Also asked at the same time on Stack Overflow - https://stackoverflow.com/questions/59820595/adding-the-first-5-values-to-compute-offset

Ok thank you, I got it. I have tried to begin, here is what I have in my function node : I saved the value inside an array, but it keeps in memory all the value from my last trials, or I'd like to empty the array at each new run of the code. So I will get the new value for my offset. If I keep all…

Please read the other recent thread on array's. It has the information you need. For example, you haven't written the context variable back so it will never change.

Ok thank you, where can I read that ? I am starting with node-red, trying to learn...

[image] Message queue node that can be indexed General Problem: small screen. Can only display 1 message. Big size of messages to queue I want the node to store/queue messages. If it gets a next command, it shows the next message. If it gets a previous command, it s…

Thank you for this link and your help, I got what I wanted !

So, at the end of the day all you want is to average the first five incoming values and store the result in the context ? If this is the case you could alternatively try using the batch node along with the join node. The batch node would group each 5 messages, without overlap. The join node would …

The node node-red-contrib-calculate looks as if it may do exactly what you want (if that is to average a reading over five samples).

Thank you. Not completly but at least it makes the mean of a number of point, then I need to get only one result to have my offset, but it's useful. Thanks

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Adding the first 5 values to compute offset

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TotallyInformation 20 January 2020 10:37 7

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Adding the first 5 values to compute offset

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