Ok, A quick simple understanding would go something like this. Access 1 is a display with some intelligence and is the part by which you access the can system (can) Closed area network. Access 2 is for Hyd. functions and all codes starting with a 2 such as 256 would be a Hyd. event code. Access 3 is for the traction motor and all event codes starting with the number 3 such as 323 would have to do with the traction system. Hope this helps.