in a transmission of surgical device 10 and of a screw drive of surgical device 10 the feedback system may determine an amount of linear force being applied to a firing rod in loading unit 20 additionally the feedback system needs to determine a linear position of the firing rod of loading unit 20 in order to ultimately determine if the torque being applied to first drive motor or second drive motor corresponds to a particular length of a staple cartridge loaded in loading unit 20 it is contemplated that an optical or magnetic encoder a linear variable differential transformer lvdt or other method may be used to determine the linear position of the firing rod during a normal operating condition of surgical device 10 a certain or predetermined force profile is expected to be seen by the feedback system in the control circuitry of surgical device 10 e g either a current v time profile see fig6 or a current v distance profile not shown in operation with the control circuitry monitoring current u201c i u201d when the firing rod of surgical device 10 is at a linear position corresponding with an end of a stroke for a particular staple cartridge length i e 30 mm 45 mm or 60 mm and.