hi,

Thanks and sorry I had some miss typing.

Just do copy-paste your code next time.

Here is a refined DAC routine and I got about 80% of accurate restored wave. About another 20% data was wrongly plotted by nine and flag branch. Why is it?

Hard to say. First of all, you need determine the point where error ocures at. I see at least two reasons:
- ADC/DAC - the analog parts of chips. Are both ADuC814 provided with good power, solid ground, stable analog voltage, enough capacitors etc?
- UART. How do you check that no error occures while bytes are transfering? Are derivatives placed on the same PCB or the each is on own one, and how they are connected to each other (buffers, transceivers etc)?

I may suggest to use ADC and DAC of the one chip firstly. Just sample data with ADC and write them to DAC at the same part without communication to second chip. Check for result with oscilloscope. Hope this gives you a hint.

Regards,
Oleg