Sending data and control lines into and out of a biosphere can be challenging.  In the past, holes have been drill through plastics walls and connectors used to seal the air in/out.  This is not possible with a none-plastic biosphere.  Since plastics can't be used in biosphere because of emitting of toxic gasses, data collection has to be reinvented.  Radio is OK, so far.

Bluetooth Schematics

I picked Bluetooth because it's cheap and easy to interface.  There are a lot of Bluetooth devices out on the market, but most of them are cheap and you get what you pay for.  In this case there is only 10 feet between the tank and the computer.  The really cheap HC-06 works OK.  If you are serious about laying out a board for a real product, don't use any of the Adriano hobby boards.  They go about 10 to 20 feet and that's it.  But for this test, one of the $3.00 boards works OK.

Most Bluetooths’ work on RS232 at 5 volts.  Not the standard RS232 voltage range from + to - 15 volts.  That means you need to change the logic levels from 15 volts to 5 volts.  Some of the instrumentation devices have an RS232 output port.  That can be channeled into a Bluetooth and collected by using an RS232 terminal simulation like Putty.   Putty can be downloaded and used for free at this site:

http://www.putty.org/

Below is a general schematics of RS232 connected to a Bluetooth device.  It is required to have a 3.3 volt power supply.  This runs the MAX232 chip and the HC-06.

Below is a picture of the current Bluetooth connected to an DO meter.

Pictured below is the data from the DO unit.  It's very cryptic and needs to be parsed.  

 

Instrumentation Methods

In this test, I'm collecting data for DO, RH, temperature and CO2.  The DO meter sends data out its RS232 port.  That is connected to a MAXS232 chip and converted to a HC-06 Bluetooth logic levels.  It's then collected by using Putty.  After, the data is imported into Excel and graphed.

Pictured below is a DO meter that is connected to a DO meter.  

When buying equipment for measuring biosphere, it's best to get something that can send collected data to an output.  A lot of the equipment can't do that.