Is the question: "How do I read the motor values last sent to the master processor?"
I don't believe there is an interface call that can do this... and I'm not entirely sure you need that info.
If you just want to know what is the current packet to be transmitted to the master processor, check out ifi_defaults.h and the txdata packet. Specifically you should be able to read the data I think you're looking for in
Code:
current_pwm01 = rxdata.rc_pwm01