A fluidic cassette detection mechanism is used for detecting the presence of a cassette (12) at a certain position within a fluidic module (10). When the cassette is inserted into the fluidic module to a certain position and orientation, the detector mechanism senses the presence of the fluidic cassette and provides an appropriate signal to the control system (28) software. The system software can then command the closing of a clamping mechanism which holds the cassette during a procedure. The fluidic cassette detector mechanism can comprise a number of mechanical probes (22), optical interrupt switches (24), and miscellaneous components including springs and screws. The probes (22) extend beyond the face of the fluidic module (10) faceplate and beyond the rear stops of the clamps. When the fluidic cassette is inserted into the fluidic module (10) far enough to sufficiently move the probes, the probes trip the switches (24) to signal that the cassette is in the correct position and orientation for the clamping motion to begin. The correct position and orientation are sensed due to the use of the probes (22) in the mechanism. The probes are spaced sufficiently apart on a diagonal, and raised beyond the rear stops of the cassette clamps, such that when both probes are moved appropriately, the cassette must be acceptably parallel to the clamps, and in the correct position, for the cassette clamping motion to begin.