An example of plant modeling in Ptolemy II is given in our Printing Press model. This application has similarities with motor control applications and involves different types of event sequences (periodic, quasi-periodic, and sporadic). The total application models the paper feed system for a high-speed printing press with both an active and a reserve roll of paper. When the active roll is nearly empty the reserve roll is brought up to speed such that the linear velocity of the paper of both rolls match. The reserve roll has a strip of tape, which is used to attach the paper from the reserve roll to the paper from the active roll. A sensor detects the position of the strip on the tape and the application computes when this strip is directly opposite the paper from the active roll. Prior to this time, a flying paster forces contact between the reserve roll and the paper from the active roll. When the tape makes contact with the active paper, the paper from the reserve roll gets attached to the active paper. Immediately following the active paper is cut. The purpose of the contact controller is to generate the signals to the contact and cutter actuators. As we discuss in , the PTIDES-based controller implements the functionality of the contact controller.