When I readout out all of the ADIS16448 registers, some values are different then expected w.r.t. the datasheet. The register update sample rate was very slow (each 2.5s). After some research I found this was due to the value of register 0x36 (SMPL_PRD). This value should be 0x0001. In my case the value was 0x0B01. The value of D, decimation rate setting was 11 instead of 0. 11 indeed corresponds with an update rate of 2.5s.
Is this a known issue that the default values are sometimes different then mentioned in the datasheet?