I use two ad9739 for synchronization. One is master and the other is slave. The figure 52 in the datasheet on page 35(Rev.B) is taken. I configure the register as the table 32 on page 47 in the datasheet. The readback value of register 0x21 is 0x99 for master and 0x09 for slave, which means both of the synchronization and Rx controller work well. However, the phase difference between the output signals of the two DACs are not constant for each time. So I read the registers of 0x16, 0x17, 0x18 of the master and all of them are zeros for each time. The same thing happens for the slave one. I also read the register 0x1B and find that the SYNCOUT_PH is changed some time for master and it always is zero for the slave. So my question is that if the synchronization component doesnot work in the slave ?