USing the Visual Studi test framework for system tests

I'm new to Visual Studio and its unit test framework and I'm unsure if it is suitable for what I would call system tests.

I have a C++/CLI class with a few methods that look something like this:

double ReadValue(int command);
void WriteValue(int command, double value);

These methods communicate with an embedded system, which is what I'm actually interested in testing. I would like to test that I can read and write to registers and that I receive error codes when values are out of range and so on.

My question is, is it wrong to use unit tests, and specifically the Visual Studio testing tools, when I'm not actually interested in testing the Read/Write methods themselves?