XBee Sensor (XS-Z16-CB2R) documentation?

XBee & XBee Gateway XBee - Zigbee
1

I’m looking for proper documentation for the XS-Z16-CB2R XBee temperature/humidity/light sensor.

In particular: how to convert the ADC values back to real world units.

I’m comparing it to a Sensirion SHT75 and SHT21 sensors. It seems humidity RH% = ADC value / 10.

Temperature had me puzzled until I noticed that it seemed ADC/10 gave temperature in F (Fahrenheit). But doing a rough calibration test … that’s not panning out… it’s out by over 4C at 0C… way beyond spec and usefulness. Perhaps each sensor is different and has to be individually calibrated??

Light I don’t care too much about, but it would be interesting to know if the ADC values correspond to any units.

So my question to anyone who is familiar with this XBee Sensor product: where is the documentation? And if there is none, please can you provide formulas to convert the ADC values back to units.

Thanks!

2

To answer my own question. I logged a support ticket on the Digi website and someone replied to the query within a few hours (great service !).

This is what I was told:
Temperature:
temp_C = (mVanalog - 500.0)/ 10.0
mVanalog = (ADC2/1023.0) * 1200

Humidity:
hum = (((mVanalog * 108.2 / 33.2) / 5000 - 0.16) / 0.0062)
mVanalog = (ADC3/1023.0) * 1200

Light:
lux = (ADC1) /1023.0) * 1200

I updated my charts … and I’m pleased to say it matches well (within spec) to a Sensirion SHT75 sensor I’m using for comparison.

3

Hey, thanks, this really helped me to make something usable from the data I’m receiving from the sensor.

Do you have experience with the battery life of this sensor. I’ve reconfigured the internal XBee to take a sample every 5 mins and go back to sleep again but I think the electronics from the sensors will keep using power even when the Xbee is asleep.

4

I have my LT/LTH sensors waking either every 10 or 60 minutes, and the batteries will last maybe 6 to 7 months.

However, you can power them with 5vdc if you don’t mind soldering 2 wires to the battery tabs. In my case, I need to power 5vdc RFID tag readers by most LT sensors anyway so I just power both from one supply. See here:
http://www.digi.com/wiki/developer/index.php/XBee_Sensors#Power_Options

An even more interesting ‘hack’ - buy one of those low cost ‘solar cell phone’ chargers which also supports USB changing of the module. They probably have a 4 to 4.5vdc lithium battery inside, which means you can use it to power the LT sensor. Protect the LT from the rain … maybe put it inside a cheap Bird House! Mine has been going fine non-stop for approaching 2 years now:
http://lynndia.blogspot.com/2010/09/solar-powered-xbee-zigbee-bird-house.html