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After taking this course, you’ll be able to:

  • Name and describe the five most common types of interrupt OBs and when to use them

  • Configure new interrupt OBs in TIA Portal and create logic to support the use of these OBs

  • Be able to identify the default settings for each type of interrupt and which properties can be modified by the programmer

  • List at least three issues a programmer must consider when using multiple interrupt OBs in a PLC program

Course curriculum

    1. 1. What is an Interrupt OB

    2. 2. What is a Cyclic Interrupt OB

    3. 3. What is a Time-of-Day Interrupt OB

    4. 4. What is a Startup Interrupt OB

    5. 5. What is a Time-Delay Interrupt OB

    6. 6. What is a Hardware Interrupt OB

    7. 7. Additional Considerations for Interrupt OBs

About this course

  • 7 lessons
  • 1 hour of video content
  • Pro Course
  • Earn Certificate of Completion

Ideal for you if…

  • You are an experienced PLC programmer and would like to add interrupt OBs to your programming “toolbox”

  • You need to add functionality that is best provided by interrupt OBs and you need to become familiar with the use of these blocks


In this course, you will learn how to use special program blocks, called interrupt organization blocks to help control the flow of logic in the PLC. This course will present the most commonly-used interrupt OBs and how they are used.

Interrupt OBs are used to control program execution flow and to provide specific timing for instructions that require scheduled execution.

The following types of interrupt OBs are covered in this course:

    • Cyclic Interrupt - this OB executes on a timed, scheduled basis

    • Time-of-Day Interrupt - this OB executes at specific times of the day to provide triggers for totalization, reporting, or shift-related activities.

    • Startup Interrupt - this special interrupt executes once on a transition of the CPU from STOP to RUN in order to perform any program initialization tasks.

    • Time-Delay Interrupt - used to perform a task upon being called by a special logic instruction, SRT_DINT.

    • Hardware Interrupt - executes when the CPU detects a hardware interrupt condition in a digital input card, and analog input card, or a function module.

Not all CPUs will have the same set of interrupt OBs available for use. Typically, the newer S7 models have a greater selection of interrupt OBs available than the older CPU models. Other programming considerations are presented that will be useful when using interrupt OBs. Issues with program execution time, understanding the priority of execution, potential for buffer memory overruns, and how to use offsets to stagger OB execution are all covered in this course.

Prepare for better pay & bigger responsibility

Testimonial title

Marcin Trojak

From my experience, I have to say that RealPars is the most professional online training program out there. The instructors are easy to follow and clearly explain PLC theories with excellent supporting visuals and real-life application examples. I like that they provide a summary after each lesson that brings together all the information and makes it easier to retain. Plus, I can train anytime, anywhere. I’m a maintenance apprentice right now, but when I complete RealPars training I’ll be ready to go after the PLC programming jobs I want.

Mohammad Khabazi

I work on electrical and instrument maintenance now, but my goal is to become a full-time PLC programmer. University courses take too much money and time. The RealPars video training method is great…the instructors are all experts and speak clearly so they keep my interest and are easy to follow. I’m eager to gain even more PLC expertise as new content is added.

Meet your instructor

Scott Sommer, PE, CAP

Scott Sommer has worked in the automation industry for over 37 years. In addition to his full-time job as Director, Automation Engineering Professional Development at Horizon Controls Group, Scott is proud to help develop the next generation of automation engineers. In his free time, he’s a RealPars instructor and an ISA trainer.

Here’s why you’ll succeed

  • One-on-one support

    Stuck or have a question? You get unlimited support from our team of proven PLC programming experts.

  • Laser-focused lessons

    We only teach you exactly what you need to know to master a PLC course. No fluff, filler, or wasting your time.

  • Experienced instructors

    All PLC training courses include step-by-step instructions from the world’s best so you can join their ranks and gain an unfair advantage.

The RealPars guarantee

  • Suited for all skill levels

    we’ll help you get the skills you need to stand out and get hired!

  • Learn practical skills

    You can immediately apply learnings and improve your results.

Start learning now

You'll get access to this course and ultimate access to the rest of the courses in the library.


  • Can I get a certificate for this course?

    Yes. RealPars will issue a Certificate of Completion (certified by RealPars) when you complete the course.

  • What is the required software?

    TIA Portal Basic V16 or higher

  • Can my employer purchase a course for me?

    Yes. Most people enroll individually, and then submit their receipt to their employer for reimbursement. However, if your employer has a tuition budget and wants to train 5 people or more, you can send us an email at [email protected] and we will help you with bulk signup.

  • Can I register for a course if I am working full time?

    Of course. All of our course content is pre-recorded, so you can work and study on your own time.

  • Do I have to travel to take this course?

    Nope! All our courses are offered online, so you can take them from anywhere in the world. All you need is a high-speed internet connection and the applicable software for your course.