TMS320F28035: TMS320F28035

user4932132 said:

1. If the CANTA register is set, but there is no data on the CAN bus, will the can data enter the transmit buffer but not be successfully sent to the bus due to arbitration?

No. CANTA bit for a mailbox will be set only after data from that mailbox has been successfully transmitted and acknowledged.

user4932132 said:

2. Does the data enter the transmit buffer or is the data sent to the bus ,  CANTA is set?

Transmission of the data must be completed and acknowledged by at least one receiver. See www.ti.com/lit/SPRA876 for details.