Use of a VXI algorithmic closed loop controller and a graphical programming language to control a film process tester

An instrumentation system that included a VXI algorithmic closed loop controller was used to demonstrate feasibility of controlling the functions of a film process tester at Eastman Kodak Company. The tester which is used by Kodak for testing innovations in film, implements the photographic film-making process on a small scale. To meet the requirements, the algorithmic closed loop controller continuously controls PID loops, monitors voltages and temperatures and responds to interrupts (such as sensing the film sample in a desired location or detecting an open door). The system also analyzes an exposed pattern by taking thousands of externally triggered voltage readings. While these functions are being performed, a PC running a graphical program written in HP VEE queries the process variables and displays the current status on the computer screen for the test operator. The results of this effort were (1) distributed intelligence where the closed loop controller does the monitoring and control while the PC program is free to respond to the operator and display the status of the test; (2) implementing the multi-tasking capabilities of the graphical programming language VEE by using multiple threads; (3) a demonstration of the capabilities and programming the HP E1415A algorithmic closed loop controller