This paper describes a method for constructing a Petri net controller for a discrete event system modeled by a Petri net. The controller consists only of places and arcs, and is computed based on the concept of Petri net place invariants. The size of the controller is proportional to the number of constraints that must be satisfied. This method is computationally efficient, and can accommodate constraints written as Boolean logic formulas in the conjunctive normal form or algebraic inequalities that contain elements of the marking and/or the firing vectors.