Question about Stimtracker Power

Dear Cedrus,
I am very happy with Stimtracker, and especially light sensor.
However I have a question.
my stimtracker is connected to responsebox (connected to Mac Pro via USB) via RJ45 TTL, and connected to same Mac Pro via USB.
when I turn on the Mac Pro, even without adaptor connected, the stimtracker’s light turns ON and it works.

maybe, the power from RJ45 make that phenomena.
Is it OK and natural?
I’m worry about connect adaptor and RJ45 power hurt the stimtracker.

Yes, this is the correct behavior. It works without effecting either device.

Then, what is the best connection?

Thank you for your reply.

If it powered without 9v power adaptor, should I detach the adaptor and just power on it with RJ45?
or should I connect both adaptor and RJ45?
or No matter how I connect them?

The 9v AC adapter should always be plugged into StimTracker. The RJ45 does not provide enough power.