I've got a big problem with my rx-28 when I tried to read its inner information. The problem is that the signal returned by rx-28 is too weak to drive the MAX-485 chip, so that the MAX-485 chip can't produce any output. And I have tried to observe the signal of 485 bus by an oscilloscope, and it can clearly indicate that, the signal transmitted to rx-28 from mega128 is much stronger than the signal returned from rx-28. That is, the difference of signal A and signal B of the returned signal in the 485 bus is much smaller.Then what's the reason? Does it mean the rx-28 has been broken and useless? I really wonder what I can do now. Thank you!