An adapter assembly includes an elongated body, a switch, a sensor link, and an annular member. The elongated body includes a distal portion configured to couple to a surgical loading unit. The distal portion defines a slot therein. The sensor link has a proximal end disposed adjacent the switch and a distal end disposed adjacent the distal portion of the elongated body. The sensor link is longitudinally movable between a proximal position and a distal position. The annular member has a protrusion movably disposed within the slot. The annular member is rotatable between a first orientation, in which the annular member prevents movement of the sensor link to the distal position, and a second orientation, in which the sensor link moves distally to toggle the switch. The annular member is resiliently biased toward the first orientation.
