The real time control of programmable devices in a manufacturing system is carried out through prepared programs. These devices have various inherent limitations on the type of activities that can be programmed. In this paper, the activities to be controlled by a program are modeled as finite state discrete event process represented by automaton and Petri net. The necessary conditions for a device to be program controllable are identified under various production requirements in a robotic machining cell. The relationships between the available programming constructs and the modeled process structures are investigated.