The thesis presents the project I developed in Termoelektrarna Toplarna Ljubljana (TE TOL) unit of the company Energetika Ljubljana.
The goal of the project was to design a program for Siemens S7-222 controller that would enable remote operation of watering lawns at location separate from TE-TOL. The user control program ensures correct functioning of the control system and adequate communication between the Siemens TC35i GSM modem, the controller and the user's GSM device.
The controller scans the memory of the GSM modem cyclically. If the GSM modem receives a new SMS text message, the controller detects it during the next scan and processes it accordingly. When the string in the message matches one of the command strings in the control code, the action required by this string is carried out. Otherwise, the SMS text message is deleted from the memory of the GSM modem.
Moreover, the control code contains a function which ensures that the controller sends an SMS text message to the user as a warning when the control system cabinet door is opened. Thus the user can be informed about any unauthorised access to the control system.
The thesis presents the technical characteristics of the used components, describes the process of creating the user program with the Step 7 Microwin software and provides insight into its functioning.
The control system can save considerable amounts of time for maintenance workers because they no longer have to water the lawn manually. They can take care of it by sending an SMS text message, regardless of their location.