DS18B20 – 2 wire configuration – 2 Temp Probe — inconsistent results June 18, 2011Posted by rik94566 in aquaponic automation, aquaponics, arduino, CAT 5 Cable, DIY aquaponics, DS18B20, Hacks, indoor aquaponics, indoor duckweed growing, indoor gardens, indoor growing, Rj45 connector, sensor, Sensor Hub, Stainless Steel Temp Probe, Standards, Temperature Probe.
Tags: float switch, microcontroller, rik kretzinger, sensor, Temp Probe, Temperature Probe
Being that I have a testing platform and the fact that I want to learn everything there is to know about how the DS18B20 behaves and performs I decided to test a 2-wire configuration using 2 temp probes. Results were inconsistent.
Here is how I configured the RJ45 testing hub. I kept the arduino side the same as in the last blog post and only changed the wire configuration on the hub side. I configured the hub the same way for both position 1 and 2.
The inconsistent results were generated only on position 2 of the hub. I have no idea why this occurs. It seems to be at random as to when it occurs in the cycles of the sketch. With results that are inconsistent it is clear that it is not a good idea to use this for important work. For 2 or 3 cycles normal temperatures report out and then the 185.00F is reported out. Strange stuff.
I am using the same Sketch posted earlier for testing 2 Probe DS18B20 sensors.
Doing a little research I found that inconsistent results are experienced when adding multiple DS18B20 sensors when using the parasite power mode, which is the 2-wire configuration I have working here. I will test other situations now and try and determine issues with this power modes and configurations