This paper deals with several selected aspects of the signal distribution in automatic checkout systems. These are: 1) The use of relay matrices as control elements; 2) The inclusion of self-checking capabilities; 3) Problems of systems integration. These aspects are not unique to automatic checkout systems. However, due to the nature of automatic checkout systems as presently being designed around digital circuitry, they find either fuller or different applications than in other types of systems. Also, while they are on the surface somewhat disconnected in nature, they tend to interrelate during the implementation of an automatic checkout system.