Problem with Parallel-to-Serial block in Simulink

I am trying to convert the input word coming out of the DQPSK Demodulator (Type : UFix2_0) to a serial stream.

So I am using the Parallel-to-Serial Block of Xilinx Library in Simulink.

But I am not able to use the block, I get the following error :

"The Simulink system period" setting on this System Generator token is not appropriate for the rates used in the design.

The current setting is: 1 An appropriate setting is: 1/2 "

I tried to change the setting the System Generator as well, but It does not seem to work as well.

Any idea where I might be going wrong. Any other approach would be helpful as well.

Thanks

Search for "simulink system period" in the Xilinx Sysgen documentation

1. http://www.xilinx.com/support/documentation/sw_manuals/xilinx13_1/sysgen_gs.pdf
2. http://www.xilinx.com/support/documentation/sw_manuals/xilinx13_1/sysgen_user.pdf
3. http://www.xilinx.com/support/documentation/sw_manuals/xilinx13_1/sysgen_ref.pdf

The getting started guide (1) shows how to calculate the simulink system periods in a system with multiple rates (which you get by using the parallel to serial block). Basically the simulink system period is the greatest common denominator of the sample periods that appear in the model. It looks like you have a conflict between how the system period is set and the periods before and after your rate changing block (parallel to serial).