A compressed air treatment device is designed to be installed in an industrial vehicle consisting of a motor vehicle that can pull a trailer. The device comprises: an inlet for air from a compressed air source; at least one air outlet which is connected to a tank that is intended to supply the service braking system; a set of electropneumatic components for distributing the compressed air which comes from the compressed air source and which is intended for the tank(s); an electronic control unit which can control said set of electropneumatic components, the control unit being connected to a computer communication bus and to various electrical components such as sensors or switches. The device also comprises: a supplementary air outlet which is intended to supply the control element(s) for the pneumatic suspension system of an axle; a supplementary set of electropneumatic components which are associated with the supplementary air outlet; control means which are integrated in the electronic control unit to control the supplementary set of electropneumatic components according to information originating from the computer communication bus and/or various electrical components.