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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.

CONDUCTIVITY:

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:

http://youtu.be/0OZzv69DhF0

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:

http://youtu.be/xhykQ61xfW0

Now on to building another harness and test it all

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