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Rotronic hygroclip

Makada Oct 23, 2021 06:08 PM


I have a Rotronic Hygroclip sensor which seems to read often 100% humidity and higher temperature values then sensors in my neighbourhood.

When i set the multiplier to 1 and offset to 0 in the crbasic code, i see when the humidity is reading 100%, the mV max value is around 2496.

Unfortunately i cant find the lowest mV value because the humidity is never 0 %.

When i use the built in Shortcut sensor, i have the same high values.

In the manual i have, it supposed to be between 496-2480 for both temperature and humidity.

Temperature range is -40 - +60

Humidity range is 0 - 100

How can i solve this issue?

With the kindest regards. 

smile Oct 26, 2021 04:09 AM

Which modell? HC2S3?

Has it ever worked well? Cable and connector are CS original?

Calibrated probe output is 0 to 1000 mV for temp & RH, if not so the probe is faulty or needs to be calibrated. The working ranges mentioned are correct, but keep in mind that shortcut puts a software filter for which the RH values ​​between about 100 and 120 are automatically set to 100. Certain weather situations occur for which there is not only steam in the air, but water droplets, in this condition many RH sensors have problems and can measure more than 100%, which is impossible. Values ​​much higher than 120 are displayed to highlight a real problem.

JDavis Oct 26, 2021 04:15 PM

You will need to calculate multipliers and offsets for that sensor based on the calibration sheet it came with. It is obviously not set to the 0-1V range that Campbell Scientific shipped them configured for.

Calculate the multiplier and offset with the same method shown in this discussion thread:


Makada Nov 1, 2021 07:45 AM

Could those symptoms be related to a very dirty filter on the top of the sensor?

I recently noticed the filter is probably not having enough air going through it.

If so, are those filters available?

With the kindest regards. 

JDavis Nov 1, 2021 06:02 PM

A dirty filter on a temp/RH sensor can make the sensor slower to respond to temperature and humidity changes. You would see it mostly affect humidity. Depending on what is deposited on the filter, you may see RH values stay high a long time. However, don't expect values over 100% humidity.

Check the exact model of sensor you have. Replacement filters are usually available. Some of the more expensive filter materials can be cleaned.

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