I simulated using example design and the settings are pN:13, pNt:15, pCS:2,pCF:1 (scramble off, subclass 1,F:4, K:32, 4lane) And checked K character and serdes input data is working normal. I need to change data bit widths to 15bit. So I just changed the sets as pN:15, pCS:0, pCF:0 and Input data as 16bit (jesd core input data) and the data is a simple counting data. And changed control bit data (in the example design) as 2 bit zeros. But in the simulation, there’re continuous K character in the MSB portion as bellows. What’s the cause of this problem ?