Return Data Buffer (73xx Controllers Only)

Data or status requested by the host is buffered in the Return Data Buffer (RDB) in FIFO mode. The FIFO is 16 commands deep.

When data exists in the RDB, the Ready to Send bit in the Communication Status Register (CSR) is set.

You can use the RDB either as a temporary buffer that holds a single return data packet, or as a small FIFO buffer. When the requested data is available in the RDB, use Read Return Data Buffer to retrieve it. You also can request multiple data items and leave them in the buffer for retrieval at a later time. If the RDB becomes full and cannot accommodate requested return data, NI-Motion generates an error and sets the Error Message bit in the CSR.