A modular surgical instrument can include a microcontroller in signal communication with an engagement sensor and a display. The engagement sensor detects the relative positioning of modular components of the surgical system. The first modular component 110 comprises a handle and the second modular component 120 comprises a shaft an engagement sensor detects whether the shaft 120 is engaged with and/or operably coupled to the handle 110. The shaft 120 can be moveable between engagement with the handle 110 and disengagement from the handle 110.
