[KenWittlief]

good question - obviously the full scale readings will be off

and Im willing to bet Analog Devices will tell you to fix that by adjusting the zero point on the output - I think there are resistors you can play with to make zero be = 2.5V - I havent looked into it

or it is possible its the analog inputs on the PIC chip that are a little off on zero - I havent played with it or done any testing - our bot seems to be good enough the way it is, so I havent spent anytime trying to make zero = 127.