Circuit board keying arrangement

摘要

An arrangement for keying plug-in circuit boards and their receptacles such that a board cannot be inserted into an incorrect receptacle. First and second projections (FIG. 1:10, 11) are located on a board (1) at ones of a plurality of first and second encoded locations (FIG. 2:A-D and A'-D'). The locations are proximate to and parallel to one edge of the board associated with a receptacle guide rail (FIG. 1:2). The guide rail contains first and second stops (12, 13) associated individually with the first and second projections. The initial projection (10) to enter the receptacle during board insertion and the initial stop (13) encountered by the initial projection and associated with the other projection (11) are dimensionally offset with respect to each other so that the initial projection bypasses the initial stop.