Digital Control Systems

Subject description

A brief history of control systems.

Areas of programmable logic control application (industry, power engineering, traffic…)

Fundamental and other logical functions: binary, memory, timer, counter.

Application of digital and analog sensors and actuators.

Flowchart and types of control: combination control, step control.

Safety measures.

Concepts and structures of PLCs. Input and output signals, addressing, data types.

Methods of user control software development: statement list (STL), ladder diagram (LAD), function block diagram (FBD).

Software development tools for user control program development and user interface design. Supervisory Control And Data Acquisition (SCADA) systems.

Communication among PLCs and other intelligent peripherals.

The subject is taught in programs

Objectives and competences

Student will learn about digital control system components and their features. He will accomplish knowledge of programmable logic controllers (PLCs), software development environment and user interfaces (HMI). Besides, student will become aware of necessity of clear requirements, perfect documentation and efficient communication among the project team.

Teaching and learning methods

Lectures (45 hours) and laboratory work (30 hours). For foreign students: consultations in English and project work.

Expected study results

Knowledge and understanding:

The student will be acquainted with the elements of control systems. He/she will understand the concepts and capabilities of programmable logic controllers and microcontrollers, as well as a variety of ways to develop control software (statement list, ladder diagram, function block diagram, assembler, C).


According to the requirements for the automation of a technological process the student will select and configure the proper hardware (programmable controller or microcontroller system).  By using the appropriate development tools, he/she will write the corresponding program to control the process and develop a suitable user interface (HMI).


In designing the control system, the student will carefully and unambiguously define the process requirements, thus avoiding some unforeseen delays due to deficient control. He/she will responsibly and with full commitment consider the safety requirements.

Transferable skills:

Through laboratory work, the student will accustom a systematic approach, appropriate documentation of ideas and solutions and effective communication with the client (technologists), co-workers and subcontractors. The student will be able to upgrade the knowledge, obtained within this course, for the realization of more demanding control systems.

Basic sources and literature

Vanja Ambrožič, David Nedeljković: Uvod v programirljive krmilne sisteme, Univerza v Ljubljani, Fakulteta za elektrotehniko, 2011.

Hans Berger: Automating with SIMATIC : controllers, software, programming, data communication, operator control and process monitoring, Publicis Publishing, Erlangen, 2009.

Heinrich Lepers: SPS-Programmierung nach IEC 61131-3. Mit Beispielen für CoDeSys und Step 7, Franzis PC und Elektronik, 2007.

Vanja Ambrožič: Mikroračunalniki v močnostni elektroniki, Univerza v Ljubljani, Fakulteta za elektrotehniko, Ljubljana, 2001.

Hans Berger: Automating with STEP7 in STL and SCL, Publicis MCD Verlag, Erlangen, 2000.

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