An adapter assembly includes a switch actuator, an actuation bar, and a latch. The switch actuator is movable between a proximal position, in which the switch actuator actuates a switch, and a distal position. The latch is movable between a first position, in which the latch permits proximal movement of the switch actuator, and a second position, in which the latch prevents proximal movement of the switch actuator. The latch is configured to move from the first position toward the second position in response to the actuation bar moving toward a proximal position.
