A mechanical ventilator system controlled by programmable logic controllers

In this paper, an example of the use of programmable logic controllers (PLC), computer programming, and computer interfacing, for teaching purposes and student projects implementation is presented. This is carried out through the design and implementation of a mechanical ventilation system that can be used on respiratory patients and controlled by a PLC. The physical control and operation of the ventilator are accomplished by the PLC via analog input and output modules located within the PLC chassis. Operator adjustment, mode selection, and patient monitoring are accomplished using a personal computer running a visual basic application designed specifically for this project. The operator interface mimics the look of a traditional ventilator control chassis. A serial data connection provides the communication path between the PLC and the personal computer. Using a PLC and a computer interface (HMI) as the respirator control system has distinct advantages over traditional microprocessor control systems. These include: the operation and adjustment of the respirator can be accomplished at a location other than the location of the respirator, alarm conditions can also be determined and evaluated from a remote location, reprogramming of the system can be easily accomplished onsite should newer respiratory modes become available. Through the use of a PLC and a HMI many different applications, similar to the one presented here, can be designed and implemented. This senior capstone design project was designed and implemented by an electrical engineering technology student as part of graduation requirements.