An instrument sterile drape (300) includes a plastic sheet (300) and an instrument sterile adapter (ISA) (510) coupled to the plastic sheet (300). The ISA includes a bottom plate (710) located on a first side of the plastic sheet (300) and a top plate (700) located on a second side of the plastic sheet (300) and joined to the bottom plate (710). The bottom plate (710) includes a mounting surface (1000) that provides a first datum plane for mounting the ISA (510) on a carriage (130) that includes actuators and a plurality of landing pads (602) that extend through the top plate (700) to provide a second datum plane for a surgical instrument (120) coupled to the ISA such that a distance between the carriage (130) and the surgical instrument (120) is controlled only by the bottom plate (710). The instrument sterile drape (300) may include a pouch (500) shaped to fit around the carriage (130) with the ISA (510) capturing the pouch (500) between the top (700) and bottom plates (710).