A portable articulated arm coordinate measuring machine (AACMM) with multi-bus arm technology that includes a manually positionable articulated arm portion, a measurement device, and an electronic circuit. The electronic circuit is configured to receive a position signal from the arm portion and to provide data corresponding to a position of the measurement device. The AACMM further includes a probe end, an accessory device, an encoder data bus, and a first device data bus. The encoder data bus is coupled to the arm portion and the electronic circuit, and the encoder data bus is configured to send the position signal to the electronic circuit. The first device data bus is coupled to the accessory device and the electronic circuit. The first device data bus is configured to operate simultaneously with and independently of the encoder data bus for sending accessory device data from the accessory device to the electronic circuit.