Exemplary embodiments include a portable articulated arm coordinate measuring machine including a manually positionable articulated arm portion having opposed first and second ends, the arm portion including a plurality of connected arm segments, each of the arm segments including at least one position transducer for producing position signals, a measurement device attached to the first end of the articulated arm coordinate measuring machine, an electronic circuit for receiving the position signals from the transducers and for providing data corresponding to a position of the measurement device, a base coupled to the second end, an upper mount portion disposed on the base, a lower mount portion fixed to a mounting structure and configured to repeatably connect to the upper mount portion and an electronic identification system configured to send identifier information identifying the lower mount portion to the electronic circuit.