CANbus message storing

[tempo]

Hello!

I need to communicate with an external device using CANbus, Layer 2standard.

I have a question regarding the stored values.

The external device sends Unitronics PLC 8 bytes of data. Let's assume the data frame first two bytes are byte 0, (most significant bit) : AA BB  and byte1 CC DD. 

I will store the values in Mi's, starting with Mi0.  How is the data saved? Does the MSB stay as MSB, so that the  MI0 value would be AA BB (43707 in DEC) and MI1 would be CCDD( 52455 in DEC).

Or the outcome would be Mi0= CCDD, Mi1=AABB? 

 

Thanks in advance!