PLC Test - Free Test, Topics, Sample Questions and Answers

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What Is a PLC Test?

The PLC test is a tool to access one's knowledge and skills in the maintenance and repair of programmable logic controllers (PLC). The test usually covers the core aspects of PLCs, such as programming, I/O devices, etc. Another substantial part of the test is dedicated to the interpretation of ladder diagrams and troubleshooting.

Who Takes the PLC Test?

PLC tests are designed for applicants of various fields, including:

• Computer Technicians
• Commercial and Industrial Equipment Technicians
• Electronics Engineering Technicians
• Electrical and Electronics Repairers

In addition, PLC questions can appear on a variety of other tests, especially those dealing with maintenance, such as the Amazon Maintenance Technician Test or the MultiCrafTest.

Ramsay Corporation’s PLC Test

Although there are many PLC tests out there, the Ramsay PLC test is by far the most popular among employers.

As with any Ramsay Test, the PLC is developed and administered by Ramsay Corporation is the largest and most professional test provider for technical assessments, used by giants such as Amazon, Walmart, and JLL. 

The Ramsay PLC test contains 50 questions on 5 different topics, 10 questions each:

• PLC and I/O Basics
• Programming Basics
• Ladder Logic 
• Peripherals and Systems
• Troubleshooting

The test is untimed, but you are expected to complete it within 1 hour.

PLC Test Sections and Sample Questions

Note: All sample questions you will see below are based on the Ramsay PLC test. 

PLC and I/O Basics

This section comprises questions related to the introduction of PLC. It deals with topics such as the different uses and applications of PLCs, safety, I/O (input and output) devices.

PLC and I/O Basics Sample Question

Pick an appropriate sensor for the circuit shown below:

 

A. Temperature sensor

B. Solenoid

C. Humidity sensor

D. Limit switch

Correct Answer

Incorrect Answer

The schematic shown is the interface between the digital output sensor and a PLC with the help of the Digital I/O module. Any digital output sensor can be interfaced with the PLC in the schematic.

A digital sensor is a device that converts the sensed physical quantity into a logic level as 0 and 1. The PLC reads this logic through the digital I/O module and performs the required actions based on the sensors’ feedback.

A solenoid is an actuator, and therefore (B) cannot be true.

Temperature and Humidity sensors are analog output sensors and require an analog input module on the PLC. Thus, (A), and (C) cannot be correct either.

Limit switches are digital output sensors and require a digital I/O module to be interfaced with the PLC. Therefore, (D) is the correct answer. 

Ladder Logic

This section deals with the visual representation of PLC programming in ladder diagrams. Most questions will require you to interpret the diagram and answer a question based upon it.

Ladder Logic Sample Question

The PLC program shown below controls a burner (B) with three gas detectors surrounding it (s1, s2, and s3).

The burner will be lit _______.

 

A. if any one of the sensors detects gas.

B. if any two of the sensors detect gas.

C. only if all three sensors detect gas.

D. The answer depends on the specific sensors detecting gas.

Correct Answer

Incorrect Answer

The Burner (B) is dependent upon three ladders. Each ladder contains two sensors. There is an “OR” condition between each combination and an “AND” condition between two sensors on each ladder. “OR” condition means “if any of the logic is true” whereas “AND” condition means both logics must be true.

Consider ladder 1. If s1 and s2 are an AND condition then the logic will be true if both of the sensors detect gas.

The same goes for s3 and s1 on ladder 2.

However, all ladders are in OR condition with the others. Therefore, if any of the ladders is true, the burner will be lit.

So, in order to light the burner, any two of the sensors must detect gas (either s1 and s2, s3 and s1, or s2 and s3).

Programming Basics

The programing section deals with the internal programming of the PLC and the functionality of its different components.

Questions in this section are often more fundamental and theoretical and require you to show an understanding of basic concepts, such as programming languages, number systems (binary, octal, hexadecimal), and components (CPU, RAM, etc.)

Don't show up unprepared! Gain the most accurate, focused preparation for your upcoming PLC test, check out the PLC Test Preparation Package.

Peripherals and Systems

The peripherals and systems section covers the devices attached to the system at the input or output source. Questions in this section may cover things like types of cables and ports, function blocks, and transmission rates (baud, bit).

Troubleshooting

In most cases, you will be required to take a PLC test as a part of the hiring process for technical positions. These jobs require a broad knowledge of troubleshooting, and this test section will be a major part of your score.

Usually, you will be presented with a scenario depicting a problem with a PLC or one of its components and will be requested to detail the actions to locate and/or solve the problem.

The Ramsay PLC PrepPack

The PLC Test Prep Package contains a total of 70 practice questions (as on the actual assessment), divided into 5 topics:

• PLC and I/O Basics - 10 questions
• Programming Basics - 10 questions
• Ladder Logic - 10 questions
• Peripherals and Systems - 10 questions
• Troubleshooting - 10 questions

Within approximately 2 hours of preparation, you will have a very good understanding of the test content, formatting, and time constraints. That will both give you essential knowledge of the content world of the PLC test and increase confidence.

Benefits

Here are the 3 main benefits of the PLC Test Preparation Package:

• Benefit #1 - Focusing on What Matters
  While the range of topics covered in the PLC test is very broad, some topics are more common than others.
  Therefore, the PLC Test Preparation Package was designed to put more emphasis on these topics. Knowing where to put your effort in advance will yield a more focused prep and a higher score.
• Benefit #2 - Not Forgetting the Theory
  Unfortunately, many experienced candidates tend to forget theoretical concepts over the years. That becomes a considerable obstacle in the written PLC test.
  The PLC test, however, will assess both your practical AND theoretical knowledge, so make sure you are prepared for that aspect as well.
• Benefit#3 - Simulating the Actual Test
  Besides knowing the material, to be fully prepared for any test you need to know, well, the test.
  Being familiar with the question structure, time constraints, and formatting of the actual Ramsay PLC Test will often be precisely the edge you need to pass. Remember that your test score will be compared to other candidates when your employer decides whether to take you on to the next stage.
  That is a benefit only an actual test simulation can give you.

Summary

The PLC is a very common test in the electrical and electronics industry and requires a broad base of knowledge to successfully pass. PLC test sections are also common in maintenance, multicraft, and electricity tests.

Being familiar with the basic definitions and components of PLCs, mastery of ladder diagrams reading, and a sense for troubleshooting are all essential for passing with a high score.