A modular conveying assembly that includes a plurality of roller bodies, a driving member, a positive stop body, and a positive stop actuator. Each roller body includes a top surface, a driven axle mounted to the roller body for conveyance therewith, a roller fixed to the driven axle, and a driven surface fixed to the driven axle. The rollers define a support plane. The driving member selectively engages the driven surfaces to affect rotation of the driven axle. The positive stop body is coupled to the plurality of roller bodies and includes a positive stop that is movable relative to the positive stop body between a first position and a second position. The positive stop extends above the support plane in the second position. The positive stop actuator selectively engages the positive stop to move the positive stop between the first position and the second position.