The CAN bus is used only for throttle and forward-reverse information. The CAN bus has error checking embedded in its protocol, important as you do not want any errors in the throttle information. The settings for data rate from the CAN bus are shown in manual for 2A1, page 21.
To send throttle info to the controller IC you have to send 3 words (so 6 bytes). The first and second words are x1 and x2 (the 16 bit info for throttle 1 and 2, see manual page 11). The 3rd word, only the LSB is used setting the forward / reverse.
If you have something and you want to test, no need to run the motor, you can use the throttle test function in the setup menu. Have a look at manual page 10, when you disable both analog throttles it will switch to receive throttle over CAN. Then the test function can be used to test this functionality and to see whether your throttle transmit is working correctly.
To get information about motor speed etc, for this it uses the RS232 (see page 21). When the controller is in motor mode the RS232 is quiet. After you send a letter the chip will respond with a continuous data stream (16 bit words, MSB first). When you send a '*' the datastream will stop.
Easiest is to send a letter (for instance 'b' for motor speed), grab the first word (so the first 2 bytes) and then shut down by sending '*' . This because it is very easy to loose synchronisation with the high speed data output...