Greenhouse Automation. Silas Harris Tsjellum van der Stok. Problem Statement. The VTC greenhouse has two individual climates, each contain fans, heaters, and vents that are controlled by an obsolete Wadsworth microSTEP greenhouse controller.
Greenhouse Automation Silas Harris Tsjellum van der Stok
Problem Statement • The VTC greenhouse has two individual climates, each contain fans, heaters, and vents that are controlled by an obsolete Wadsworth microSTEP greenhouse controller. • VTC has requested a new control system that will interface seamlessly with the greenhouse, allowing full manual override when necessary
System Configuration Potentiometers will be mechanically fastened to the roof and wall vents, relaying precise position feedback 220V AC motor opens and closes roof and wall vents. (4) total motors 120V exhaust fans lower interior temperatures in conjunction with the vents Thermocouples placed throughout the zones will precisely measure temperature
System Configuration (continued) Reznor heaters contain 2-speed fans. Two humidity sensors will measure relative humidity in each climate, relaying this information to the controller Preexisting relay panel consists of (40) 5 amp relays, connected to each load, i.e. heaters, fans, vent motors, etc.
1nd Solution The first possible solution includes a Click PLC, and an analog user interface. Downsides include the archaic UI, and relatively high cost. Expansion modules may be required to interface with further accessories. Benefits include the simple programming (ladder logic), and seamless relay integration.
2rd Solution The second possible solution is the usage of a microcontroller, such as an Arduino or a Freescale 8 or 16 bit MCU. Advantages of this solution are the flexible programming (C language) and very low cost. The UI would be similar to that of the PLC, analog gauges and lights to indicate output conditions. Disadvantages would be the UI and the potential issues found in CodeWarrior.
3st Solution The third solution is to utilize a National Instruments USB-6212 and a laptop computer to interface with the sensors and relay panel, as well as offer a professional user interface. Potential issues are the required computer to display the GUI, as well as high cost. Benefits include simple programming (LabView), as well as GUI.
Conclusion • To conclude, we have chosen option three. We feel that using LabView in conjunction with a DAQ would offer the best end user interface and provide a relatively simple programming method.