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A new, freely programmable, scalable control system for academic research purposes was developed. The intention was, to have a control unit capable of handling multiple PT1000 temperature sensors at reasonable accuracy and temperature range, as well as digital input signals and providing more powerful output signals at 230V AC than conventional control units. To take full advantage of the system, control-loops are run in real time. The whole system runs independently of a personal computer. The two on-board RS232 connectors allow to connect further units to use more sensors or actuators or to connect other laboratory equipment, as required. To allow usage for long-time experiments, systematically electronic components with low failure-in-time (FIT) rate have been chosen in order to achieve high life expectancy. This paper describes the third prototype, which now provides stable measurements, and an improvement in accuracy compared to the previous designs. A rough estimation about the expected mean time between failures is given. As test case, a thermal solar system to produce hot tap water and assist heating in a single-family house was implemented. The solar fluid pump was power-controlled and several temperatures at different points in the hydraulic system were measured and used in the control algorithms. The hardware design proved suitable to test several different control strategies and their corresponding algorithms for the thermal solar system.
A new, freely programmable, scalable control system for academic research purposes was developed. The intention was, to have a control unit capable of handling multiple PT1000 temperature sensors at reasonable accuracy and temperature range, as well as digital input signals and providing powerful output signals. To take full advantage of the system, control-loops are run in real time. The whole eight bit system with very limited memory runs independently of a personal computer. The two on board RS232 connectors allow to connect further units or to connect other equipment, as required in real time. This paper describes the software architecture for the third prototype that now provides stable measurements and an improvement in accuracy compared to the previous designs. As test case a thermal solar system to produce hot tap water and assist heating in a single-family house was implemented. The solar fluid pump was power-controlled and several temperatures at different points in the hydraulic system were measured and used in the control algorithms. The software architecture proved suitable to test several different control strategies and their corresponding algorithms for the thermal solar system.
More and more old machines have the problem that their control electronics’ lifecycle comes to its intended end of life, whilst the mechanics itself and process capability is still in very good condition. This article shows an example of a reactive ion etcher originally built in 1988, which was refitted with a new control concept. The original control unit was repaired several times based on manufacturer’s obsolescence management. At start of the retrofit project the integrated circuits were no longer available for further repair of the original control unit. Safety, repeatability and stability of the process were greatly improved.