They have succeeded in SPI writing/reading for a single chip and they have
succeeded in SPI writing for multiple chips in daisy-chain.It seems that the
operational timing/steps for the read-back in daisy-chain mode is not explained
in detail in the datasheet.
I am not sure it is possible to use readback in daisy-chain mode and I’m not
aware of it being offered with other DACs that have a daisy chain mode.
Readback is difficult to implement with daisy-chain as the register data
clocked out of the first device could appear as a command to the second device
causing unexpected behavior.