Measuring unit, management unit, drive unit, drive system, and measuring apparatus

At least one of measurement of rectilinear or rotational displacement of an object, and rectilinear or rotational displacement driving of an object is performed by an apparatus which includes a unit for outputting a displacement signal upon rectilinear or rotational displacement of the object. The unit is able to be signally disconnected/connected from/to an external signal processing device, and is adapted to output the displacement signal to the connected signal processing device. The apparatus includes a memory provided in the measuring unit. The memory is able to store at least management information that pertains to the unit, and at least the management information is able to be read out from the memory by access from the external signal processing device.