Hi dlloyd,
The power supply is 12 V, but the output signal is an open collector type circuit, so I just connected it to 5V from the UNO's power. I don't know how low it will go though, 3.3 V seems pretty low, but it may work. Even if this will work, I still need to get the data logger shield working, which I'm currently working on. I found a thread on the Due forum, but I'm having any luck on it so far...