ADS1248 Read data problem

Hello Support,

I ve got some problems to read out the three bytes of the ADS1248 conversion buffer.
To read and write the registers works fine.

If i try to read out the register i get the right output code. But if i read out the conversion results, i allways get three times the same byte value.
I supose that normaly i would get different byte values?!
This causes a resolution of only 2^7 =128.This leads with a reference signal Ref=2.048V  to a readout value of only 0.016V per bit.
It seems i can only read the MSB. (Page 52 Datasheet Figure 75)

MCU= MSP430f2274

To read 3 bytes i programed the following code (readADbuf()):

    unsigned char datab[3];
    volatile long shift;
    int x;

       for(x=0;x<=3;x++){
        while(!(IFG2&UCB0TXIFG))
        UCB0TXBUF=0xFF;            //dummy NOP
        datab[x]=UCB0RXBUF;
        }
       
        shift= ((long)datab[0]<<16)+((long)datab[1]<<8)+((long)datab[2]);

the result of this example is as followed:

datab[0]=0xFE
datab[1]=0xFE
datab[2]=0XFE

If i change the input voltage i always get 3 times the same Hex output.

The SPI clock = 250kHz

To  initialze the system.
I do it as followed (main()):

    P2DIR |= Start+MR;
    P2DIR &= ~0x04;
    P2OUT = Start+MR;  //Start and Reset Pin High
    P3OUT &= ~CS;   // CS LOW

systemCTL(RESET); // sent RESET
systemCTL(SDATAC); // stop reading data continuosly
systemCTL(SYSOCAL);// Offset system calibration

while(1){
    systemCTL(RDATA); //sent SPI command Read Data
    readADbuf(&data); //read AD conversion buffer
    voltconvert(data);
    timer(1500);
  }

i dont know what is going wrong.

Best regards

Patrick B.