Unpacking it revealed a variety of contents, including a cable, power supply, usb interface with power supply, case, documentation, software, and a very large sensor and sleeves. (To be welded into place)

And I do mean large! Jim and I were both expecting something smaller than a D-cell MagLite, guess we’ll have to pay more attention to dimensions next time!

After getting everything installed and downloaded, we were EXTREMELY excited to see it give us reasonable readings for a bucket of seed we have and for my Nalgene water bottle. It really looks like we finally (8 months later?!) have a sensor to build the rest of our solution around. More to come!

This only served to emphasize the importance of proper abstraction and encapsulation in my architecture and implementation. Of course, this is something of a challenge given the proprietary nature of expensive moisture sensors, but I’m doing my best.

Unfortunately, my effort to open source a library interfacing with the sensor was denied by the company, which claimed it would reveal too much of their intellectual property. (Which they give away readily without NDA.) On the upside, they already had a .NET library for interfacing with the sensor, saving me a lot of tedious serial I/O programming. I’m currently in the process of abstracting and wrapping up this dll into a sensor service using WCF to be deployed on inexpensive embedded hardware near the installation of the sensor(s), leaving the data processing and visualization to a more powerful station that will connect to all the sensors on the LAN. With some more research I hope to find an OSI approved license that will allow me to open source the sensor service, leaving the proprietary Hydronix information wrapped in their dll.

Unfortunately, I don’t think the data analysis, control, and visualization module of the application is a good candidate for open source as the visualization component is proprietary and has a price tag. Furthermore, controlling the moisture content of seed to be pressed for biodiesel isn’t exactly a common activity, and would likely appeal to a small number of other people at best. However, I’m very excited to likely release the sensor service as I’ve benefited a lot from the open source community over the years.

Open source issues aside, the project is progressing if a bit slowly and unsurely. If the sensor arrives soon I’ll be able to test the interface code I’ve written, and if not I’ll be coding up a virtual sensor so that I can begin to test the analysis, control, and visualization. Unfortunately, the specifics of these activities are dependent on what techniques actually end up successfully measuring the moisture content of the seed so I’m hopeful the sensor arrives soon.

The idea is to use a microwave-base sensor to determine the moisture content of vegetable seed being pressed for oil for feedstock for a biodiesel processor, and add water as necessary to optimize the mash byproduct and the performance of the presses. It turns out “cheap” (only in reference to their German alternatives) seed presses are picky about the moisture content of seed, and like to clog up if it’s not close to 12%. Of course clogging requires stopping the entire operation while someone spends an hour cleaning it out. Which is where we come in! Simple .NET software running on cheap hardware with a Phidget interface kit for I/O will read values from the microwave sensor and add the appropriate amount of water. Easy! Right?

Already we’re running into difficulties. For starters, the microwave sensor has a digital interface but so far the manufacturer hasn’t released a protocol specification to us. Or even, gasp, a library. Another problem is that while your washing machine can be off a gallon or so when filling up for the wash cycle, our application can’t be and thus is vulnerable to pressure variations. For example, flushing the toilet could clog the seed presses resulting in an hour of down-time. Oops!

In any case I’m really excited about the project, it already has people lined up to use it, and I’ll be getting the chance to work with a variety of technologies while finding solutions and choosing my own direction, other than the loose guidance of Jim.