Compare two byte arrays

In the first case, you're comparing a std_logic_vector to an array of std_logic_vector. Doesn't work.

In the 2nd case, you're comparing a std_logic to a std_logic_vector. Doesn't work either.

I assume the problem is that the type of com_str is wrong. I guess it should really be this:

signal command: std_logic_vector(7 downto 0);

That would, from the context, make more sense to me.