An IC unit includes a scale increment reading module that is configured to: detect, when an indicator in an instrument rotates, rotation of the indicator, and convert the rotation into rotation data; and an antenna that is configured to transmit the rotation data wirelessly from the IC tag unit to a reader. The instrument includes a scale plate, scale increments on the scale plate remain viewable when the IC tag unit is affixed to the instrument. The instrument includes a transparent cover plate, the IC tag unit is affixed to the transparent cover plate when the IC tag unit is affixed to an instrument. The IC tag unit is calibrated by rotating the IC tag unit until an indicating portion of the indicator overlaps a first pointer on the scale plate.