Band Pass filter output data

I'm also not using the FIR compiler, but your results look meaningful. Apparently the test signal as well as the output are sampled with the tenfold of the filter sampling rate, most likely because the test case is for the fully serial FIR compiler option, that uses 10 clocks for a sample. The waveform, you previously posted (and asked, why it's discontinous) shows a 50 Hz sine sampled at 1000 Hz, as requested.

The output scaling comes from selecting "Full resolution" for the output numbering system. Full resolution means something like nInputBits + nCoeffBits + log2(nCoeff), in this case it's 20 Bit, as the Megawizard shows for your design. So everything seems to be in normal operation.

To my opinion, the filter performance is rather bad, particularly the high frequency attenuation. But it's an obvious result of providing too few coefficients for a fs/fc ratio of 20.

There may reasons to use a FIR filter, but I would prefer IIR in this case.