A magnetostrictive sensing instrument comprises a probe including a tube having a near end and a distal end. A magnetostrictive wire is in the tube. An adaptor at the tube near end includes a probe circuit comprising a drive circuit for the magnetostrictive wire, a pickup sensor, a preamplifier and a memory circuit storing calibration parameters for the probe. An instrument housing includes a control circuit. A connector is operatively disposed between the instrument housing and the adaptor and comprises electrical conductors for connecting the control circuit to the probe circuit.