Professional development

Top 30 supervisory control and data acquisition (SCADA) technician interview questions and answers for 2019

Kurt Ellzey
December 20, 2018 by
Kurt Ellzey

As control system architecture plays an increasingly important role in critical infrastructure, the importance of the role of Supervisory Control and Data Acquisition (SCADA) technicians will increase in the coming years as well. This will bring with it a marked increase in the demand for these positions and the importance of the SCADA technician interview.

This article will detail the top 30 SCADA technician interview questions and answers for 2019 and a general explanation of what you should give or what can be expected from you for the answer. The questions and answers will be categorized by their respective level of difficulty: Junior Technician, Mid-Level Technician and Senior Technician. After reading this article, you will have an all-around better chance to ace the interview and get in on one of the most exciting new industries taking shape today.

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Level 1 – Junior technician

This level of SCADA technician questions will begin to delve into your professional background and give you a solid opportunity to show that you are a good choice for this position. Instead of general questions that could apply to any job, much like how the lowest level of job interview questions typically do, this level of questions will at least touch on SCADA in some way. Questions like these are crucial because they let you elaborate on your experience, and it has been said that experience is one of the important factors in hiring SCADA technicians.

1. How long have you been working with SCADA?

This may seem like a simple straightforward question, but what they are trying to read between the proverbial lines is how comfortable you are with SCADA systems. Just give them an honest answer, preferably demonstrating your comfort level to some degree. A question like this is as much of a warmup for you as it is the interviewer, so don’t sweat it too much.

2. What Are Industrial Control Systems?

“Industrial control systems” is a general categorical description of several different types of control systems used in industrial process control. SCADA is one form of an industrial control system that is used widely today. A question like this is just trying to test the waters and see where you stand in terms of familiarity with this kind of technology.

3. What different levels of SCADA are you familiar with?

This is another question that coaxes out your experience with working within the SCADA system framework. There are five different levels of the SCADA system:

  • Field level devices/instruments, such as sensors
  • Remote Terminal Units, or RTUs
  • Main control station
  • Communication system between RTUs and the main control station
  • Computer systems to process data to be displayed to the SCADA operator

4. Based on your experience, how important is delegation of duties with regard to being a SCADA technician?

This question is trying to flush out more about your direct experience as a SCADA technician (if you have it, that is). What you want to tell them is that delegation can be a good way to perform certain tasks as a SCADA technician. These tasks are dependent upon how the particular SCADA system is set up. As a SCADA technician, you can automate different tasks and SCADA is easy to configure it how you want it.

5. Are you flexible regarding scheduling?

Flexibility is key to being a successful SCADA technician. In the real world, SCADA technician work can be demanding but may be subject to times when there is less work to be done than other times. Many employers respond to this by requiring a flexible schedule for their SCADA technicians. Be prepared for this and definitely let them know you are flexible.

6. What is programmable logic controller (PLC) technology?

Programmable logic controller (PLC) technology is a robust industrial computer. PLC processes signals from remote devices and instruments and is one of the five necessary components of a SCADA system.

7. How important is a quick response when system emergencies occur?

A quick response is vital when SCADA system emergencies occur. In fact, depending on the emergency, a quick response may be the difference between rectification and a disaster. This question also highlights the importance of flexibility of scheduling because emergencies could occur at any time.

8. Remote work may be possible as a SCADA technician, but what are some examples of times when it would not be feasible to work remotely?

While you may be able to work remotely as a SCADA technician, situations may arise where working remotely will not be suitable. This may be when there is an emergency that requires operator input on-site or when there is a power outage. Playing again off the notion that flexibility is necessary, a question like this just further outlines your suitability for the role, so do not sweat it.

9. Tell me about a time when teamwork was necessary to solve an issue, particularly involving SCADA

Communication, teamwork and problem-solving are essential qualities of a successful SCADA technician. If you have previously worked as a SCADA technician, talk about a time when you had to work with teammates to solve a SCADA-related issue. If this is your first SCADA position, focus on a time when you had to work with teammates to solve a problem – if you can, choose an example involving technology or automation so your answer will be as relevant as possible.

10. Aside from professional experience, what makes you a good candidate for this SCADA technician position?

When you are asked this question, the interviewer is trying to gauge your innate ability to take on this role. Try to bring up all of the qualities required for a successful SCADA technician that you possess – these qualities include that you are dependable, responsible, responsive, quick thinking, a good problem-solver and able to work well as a member of a team. Have a combination of these, or all of them, on the back burner in your mind so when they ask you this question it comes out easily. Sometimes, the confidence that you answer a question with is another thing they are looking for.

Level 2 – Mid-level technician

The Mid-Level Technician level of interview questions are, as you can imagine, a little more difficult from the Junior Technician level. Do not let this scare you off, though, because really all these questions are is just a little more SCADA-focused and will require a little more detail in your answers. As the levels increase, the questions get more SCADA driven.

11. What are some benefits of using object-oriented graphics?

Object-oriented graphics make customization of a SCADA system a breeze for a technician. Object-oriented design tools are powerful and allow you to easily arrange, draw, align, space, rotate and generally manipulate objects. InTouch is usually used for this, which supports ActiveX objects. This makes the tool even more powerful.

12. Why are SCADA systems implemented in the first place?

While you could probably come up with many reasons, below is a list of five answers that will help you seal the deal for sure:

  • SCADA improves the performance of plant operations
  • SCADA provides protection of plant equipment
  • SCADA improves the productivity of plant personnel
  • SCADA receives, processes and displays information very fast, allowing for technicians and operators to make fast decisions
  • SCADA offers more energy savings

13. Which SCADA have you worked with?

There are many different SCADA setups available, and they operate in different industries. Be sure to mention the name of the SCADA setup used, as well as the industry that it was in. Buttress your answer with any industry specific caveats that there may have been as different industries have different needs.

14. Which specific PLC have you used for communication within a SCADA design?

This question is trying to gauge your familiarity and comfort level with different PLC communication set ups. Make sure to bring up which specific PLCs you have experience with – Siemens, Rockwell and so on. If you can, try to find out which PLC the organization uses and if your experience is with another PLC, then draw parallels where possible.

15. Please describe the specific PLC-SCADA communication setup you have used

Questions like these are the some of the best for interviewers to determine SCADA aptitude, as it focuses on operational understanding of a SCADA system. SCADA systems use require the use of PLCs for communicating with field devices, so you definitely understand the communication setup between PLC and SCADA. Wow your interviewer by mentioning that PLCs can also be referred to as Smart RTUs.

16. What Is SCADA historian?

SCADA Historian is a data-collecting service responsible for collecting data from the different SCADA devices. This data is then stored in the time series database and can then be used to study SCADA performance.

17. What Is DDE?

Dynamic Data Exchange, or DDE, is a communication protocol which can implement client-server communication. DDE gathers and distributes live data including instrument reading, production measurement and so on. DDE can be used as a source of information to better analyze overall SCADA performance.

18. Can you name the leading SCADA companies?

This is a bit of a trick question. For one, you already have named the SCADA systems you have experience working with, and for two, this question seems to try to further gauge your familiarity with SCADA as a whole. Below are the leading SCADA companies:

  • Siemens WinCC
  • Invensys Wonderware InTouch
  • Intellution iFix
  • Allen Bradley RS View
  • Rockwell
  • GE Fanuc Simplicity

19. What is considered the SCADA master unit?

Without a doubt, the SCADA Master Unit is the Centralized Monitoring System, or CMS. It can be thought of as the brain of SCADA.

20. What does the centralized monitoring system do exactly?

Centralized Monitoring System, or CMS, is responsible for collecting information from the remote stations and devices. This information is then processed, and the CMS generates necessary actions based upon said information. It is quite literally like decision making part of your brain on steroids.


Level 3 – Senior technician

So here we are – at the doorstep of the third and final level of interview questions. Keep in mind that the Senior in Senior Technician does not literally mean a Senior Technician role, but rather the most reasonably difficult interview questions that a SCADA technician will be faced with. These questions will require you to dig even deeper into your internalized SCADA guide book, and you will have to demonstrate a professional understanding of SCADA as a technician. Buckle up and get ready for the final ten questions and answers!

21. What Are SCADA’s Two Different Communication Configurations?

There are two different configurations in SCADA – the Master/Slave system and the Interrupted system. In the Master/Slave system, the master is in complete control of communications and regularly sends and receives data to the slaves. In the interrupted system, each slave transfers data to the master if the slave exceeds a limit or if a significant change is detected.

22. What is data acquisition?

In SCADA, data acquisition is the method used for accessing and controlling data of the controlled and monitored equipment. Accessed data is then sent to the telemetry system so it can be transferred to SCADA’s different sites. The data can be in either analog or digital form.

23. What are the two different licensing patterns used for SCADA software?

There are two different types of licensing patterns used: Software Lock and Dongle Key. With the Software Lock pattern, the software code is the license. This is normally entered during installation. For Dongle Key, the licensing is controlled by a hardware lock which can be added to a PC communication port.

24. Let’s say you are hired. You show up to work and you do not like the way that the human-machine interface is presented to you. What do You do?

This is quite easy actually. The Human Machine Interface, or HMI, usually includes a drawing program that will let you change the way the points are presented on the mimic diagram. The ease with which you can change the way information is presented in the HMI is a strong SCADA selling point for sure.

25. Generally speaking, can changes be made to the SCADA system without shutting down?

A good thing about SCADA is that there is no compiling. What this means is that the changes take place immediately without shutting down. In cases where there are redundant servers, any changes made get automatically sent to standby servers.

26. Is redundancy necessary in SCADA? If so, what redundancy plan would you use?

Redundancy is very much necessary in SCADA. If I were implementing a specific redundancy plan, I would use triple-mirrored redundancy. What this means is that there is no extra database configuration or back end programming required – all SCADA functions will work from the redundant or standby server.

27. As you know, support nodes may be at remote locations. How can you support nodes at these remote locations?

When remote users connect, it is either by ViewX or WebX. SCADA connections are set up to be operated over low-bandwidth WAN. Data is transmitted to clients with the publish and subscribe method and report is by exception. The result is increased performance for these remote users.

28. What happens when a main server fails?

When a main server fails, it is not as fatal as it may sound. When it happens, clients automatically will connect to a standby server as soon as the failure is detected. This process is transparent to the user.

29. How are alarms reported by the control and monitoring system (CMS)?

Alarms are displayed on the alarm banner located at the bottom of the page and are visible on any page. SCADA contains an internal Alarm Management System that allows you to redirect, sort and filter alarms. Custom alarm lists are available, which would let you view alarms for only specific breakers or substations when needed. Customization of alarms is another positive point of SCADA.

30. What do you see as the future of SCADA?

The future is very bright for SCADA. I see SCADA becoming the control system of choice for many smart cities and municipalities. Not to be left out, automated industries will continue to choose SCADA, and I can also see expanded use of SCADA within the automotive and food industries. Aside from SCADA’s powerful capabilities, the ease with which technicians can make changes to SCADA only adds more wind to its sails.


SCADA may be considered the way of the future with regard to ICS. It has broad applications, and SCADA technician jobs will be opening up all over the United States and the world as a whole. If you are going to be interviewing for a SCADA technician position, take the nuggets of interview question-and-answer gold above and you will be very competitive if not a shoo-in for the position. Just relax, review and get the SCADA technician job of your dreams!

Cybersecurity interview guide

Cybersecurity interview guide

Ace your next interview with tips from our free ebook, “How to stand out, get hired and advance your career.”


Kurt Ellzey
Kurt Ellzey

Kurt Ellzey has worked in IT for the past 12 years, with a specialization in Information Security. During that time, he has covered a broad swath of IT tasks from system administration to application development and beyond. He has contributed to a book published in 2013 entitled "Security 3.0" which is currently available on Amazon and other retailers.