ads1248 problem

hi

i don't konw  whether  my  ads1248 wreg command is correct.  how can I make sure the spi communication is right? 

my code is below.   the /drdy  is  always  1. the adc1248 result is all 0. 

 ADC_CS_LO;
 DelayNmSec(1);
 ADC_RST_HI;
 ADC_RST_LO;
 ADC_RST_HI;
 
 DelayNmSec(1);

cmdbuf[0]=WREG|MUX0;
 cmdbuf[1]=0x0E;    //
 cmdbuf[2]=0x01;  //mux0
 cmdbuf[3]=0x00;    //0B00001010;    //vbias  ain1,ain3
 cmdbuf[4]=0x20;  //mux1
 cmdbuf[5]=0x00;    //0B01011111;          //sys0 pga =32 , 2000sps
 cmdbuf[6]=0x00;    //ofc0
 cmdbuf[7]=0x00;    //ofc1
 cmdbuf[8]=0x00;    //ofc2
 cmdbuf[9]=0x00;    //fsc0
 cmdbuf[10]=0x00;   //fsc1
 cmdbuf[11]=0x00;   //fsc2
 cmdbuf[12]=0x00;   //0B00000000; //idac0
 cmdbuf[13]=0x04;   //0B00001000;  //idac1
 cmdbuf[14]=0xCC;   //GPIOCFG
 cmdbuf[15]=0x01;   //GPIODIR
 cmdbuf[16]=0x00;   //GPIODAT
 
putsSPI1(17,&cmdbuf[0]);

ADC_CS_HI;

 DelayNmSec(1);
 
 ADC_CS_LO; 
 ADC_START_LO; 
 ADC_START_HI;
 DelayNmSec(1);
 ADC_START_LO;
 DelayNmSec(12);

while(ADC_DRDY_STAT);
 
 WriteSPI1(0x12);
 for(i=0;i<3;i++)
 {
  WriteSPI1(0xff);
  while(!DataRdySPI1());
  DelayNmSec(1);
  RX_BUF[i] = ReadSPI1();
 } 
 ADC_CS_HI;
 
 for(i=0;i<3;i++)
 {
  WriteUART1(RX_BUF[i]);
 }