Each serial communication port is double-buffered with two 256-byte buffers, synchronized with the ID pattern. One buffer fills while the other is multiplexed into the PCM stream. The data can be commutated normally, sub-commutated, or super-commutated, treating each byte as a PCM word.
Each data byte received can be configured as:
- A single PCM word, with the 8-bit RS422 data placed in the LSB of the PCM word.
- Two consecutive RS422 words packed into a single PCM word, with the first byte containing the 8 MSB and the second byte the 8 LSB.
- A full RS422 buffer can be commutated into each PCM frame as a burst.