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HARNESS TESTING — very important — DS18B20 April 20, 2012

Posted by rik94566 in 1-wire, aquaponic automation, DS18B20, One-wire, sensor, Stainless Steel Temp Probe, Temperature Probe.
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use your multimeter

Now that I have constructed an addition harness I need to make sure it works.  Two (2) tests needs to be performed.  Conductivity and ohm confirmation of the resistor value through the connections.


This test will let me know that all my connections are correctly connected and signal is flowing through the wires and working the way I configured them.  If not,  I will need to correct the problem and retest until the connections are working correctly.

Here is a video of the testing I did:


ohm Value Testing:

This is important with DS18B20 probes.  It is important because the DS18B20 IC’s  are sensitive when it comes to resistor values and there  tolerance levels.  I bought some very cheap 4.7K ohm resistors and did not know the tolerance level.  Hooked everything up and the probe did not work.  I had to trouble shoot all the connections and everything was working – then I swapped out a resistor that I knew worked and had specs on and bingo everything was working.  I have no problems using resistors with a 5% tolerance rating.  They will give you some swings in value readings, but the DS18B20’s will work very well it you stay in this tolerance range.

Here is a video of how I tested for ohm’s:


Now on to building another harness and test it all



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