A method of reading machine-readable marks on a movable support and object of a sample instrument. The method includes capturing a first image of the moveable support as the moveable support moves from a first position to a second position using an image capture device; determining whether a first fiducial machine-readable mark on the moveable support is in the first image; determining, when the first fiducial machine-readable mark is in the first image, whether a first machine-readable mark on a first object coupled to the moveable support is in the first image at a predetermined position relative to the first fiducial machine-readable mark; and associating information decoded from the first machine-readable mark on the first object with a first location on the moveable support associated with the first fiducial machine-readable mark.