Greenhouse Automation - System Architecture

System Topology

The diagram below depicts the overall system topology as implemented in our greenhouse.

On the left of the diagram is shown the Environmental Manager component, consisting of a Raspberry Pi computer module with an attached temperature and relative humidity sensor, and hosting custom environmental management software. Communication with the automation controllers is accomplished using the Raspberry Pi RS232 serial port. A driver converts the RS232 data stream to RS485 in order to provide increased resistance to electrical noise. The RS485 connection is combined with 12 VDC power lines into the communications and power distribution cable for the system.

In the center of the diagram is shown the four Vent Controllers (one controller per vent) and the Fan Controller which provides variable speed power to the three greenhouse fans.

On the right of the diagram is shown the Equipment Interface Module (in the final stages of development) which can take readings from up to twenty thermal sensors placed in the growing area, can control up to six water valves and controls, can control up to three variable 120 VAC 4A loads such as fans or motors, and can receive input from up to three switches or other discrete sensors using 5-48 VAC/DC.

Controller Features

Each controller contains a tiny multi-featured specialized computer designed for sensing and generating electrical signals (commonly called a microcontroller) combined with appropriate device interface circuitry. Controllers can be addressed individually, by device type (vent controller, fan controller, etc.), or all at once. The communication network can support up to sixteen devices of each type. The command set for each controller includes directives for the individual device, for all devices of its type, or for any device (device identification, basic control, communication statistics, etc.). Transactions on the communication network contain an integrity check field to further protect against errors.

Continue to Vent Controller

This page last revised on 05/05/2018