In accordance with the present invention, a modular patient care system provides patient monitoring and the supply of therapeutic requirements. Specifically, the system is comprised of an interface unit and a plurality of patient functional units. The interface unit provides an interface between the user and the system, and may be configured and adapted to provide different levels of functionality. Interface units with different levels of functionality may be interchanged so as to provide greater flexibility, safety, and cost effectiveness. Each interface unit contains interface ports for the transfer of information such as drug libraries, system configuration values, and event history. The functional units are internally programmed and controlled so as to provide a high level of system modularity, and require only power and interfacing functionality from the interface unit.