Temperature Readings Resolution Changing

We have three of the IoT Long Range Wireless Temperature Humidity Sensor reporting back to a single MQTT Gateway. Periodically, the resolution on the temperature seems to change (see attached screenshots for three sensors in the same timeframe). This does not occur on all three at the same time. Typically all three are reporting normally, but there are times when 1 out of the 3 is not reporting temperatures to the same resolution as before.


The MQTT Gateway submits temperature readings in Celsius, so I assume you are doing some conversion of the data. Perhaps this data conversion is rounding off the decimal places occasionally resulting in the graph charting looking more digital than analog.

Could you try graphing the celsius readings directly from the sensor without converting them to see if the problem persists?

That a great question! I too wondered that and looked at the raw values in C, before the expression that converts the C to F, and noticed that the values in C were showing the same behavior. Here is all three in C in on graph.

Assuming that all three plots are on the same time scale, it seems that the top plot has a lot less samples than the other two. Could that influence the interpolation used by the charting program?

The top graph is a sensor in a small office. The remaining two graphs are sensors on the production floor. I believe that the temperature swings experienced on the floor are far greater than the small office.

Here is another screenshot, temperatures in C as reported by the MQTT broker. The top three graphs are reporting to NCD “MQTT Gateway 1” and the bottom three graphs are reporting to NCD “MQTT Gateway 2” in a different building. The resolution of the temperatures being reported by a sensor connected to MQTT Gateway 1 sometimes is reduced to 1 degree C and sometimes fixes itself.