Beginner

PLC Basics

PLC Programming | How to Read Ladder Logic

Ladder Logic is one of the top 5 most popular types of PLC programming languages used in manufacturing environments. Before Programmable Logic Controllers, manufacturing plants employed relay-based circuitry to energize different loads based on how the relays were wired together. Relays were costly, required constant maintenance, and could not be easily reconfigured. As PLCs took over this process, it was essential to keep a similarity of the old system; thus, ladder logic was created as the first PLC programming language.

Vladimir Romanov
April 9, 2020
Beginner
Ladder Logic
Featured Tutorial

PLC Programming | How to Read Ladder Logic

Ladder Logic is one of the top 5 most popular types of PLC programming languages used in manufacturing environments. Before Programmable Logic Controllers, manufacturing plants employed relay-based circuitry to energize different loads based on how the relays were wired together. Relays were costly, required constant maintenance, and could not be easily reconfigured. As PLCs took over this process, it was essential to keep a similarity of the old system; thus, ladder logic was created as the first PLC programming language.

Vladimir Romanov
April 9, 2020
Featured Tutorial

Ladder Logic Symbols | PLC Programming in RSLogix 5000 Studio Allen Bradley

Ladder Logic is one of the most common PLC programming languages. The standards of the language are well documented by the International Electromechanical Commission (IEC) in the exhibit 61131-3. However, official documentation of the ladder logic symbols isn’t easy to digest and doesn’t provide concrete examples of each one.Ladder Logic symbols are foundational elements that are memorized by every plc programmer. They’re essential to know if you plan to do any work with this PLC programming language.In this tutorial, we will discuss each symbol, the functionality it brings to the ladder logic plc programming language as well as illustrate two examples where they may be used.

Vladimir Romanov
April 9, 2020

PLC Programming | How to Read Ladder Logic

Ladder Logic is one of the top 5 most popular types of PLC programming languages used in manufacturing environments. Before Programmable Logic Controllers, manufacturing plants employed relay-based circuitry to energize different loads based on how the relays were wired together. Relays were costly, required constant maintenance, and could not be easily reconfigured. As PLCs took over this process, it was essential to keep a similarity of the old system; thus, ladder logic was created as the first PLC programming language.

Vladimir Romanov
April 9, 2020
Beginner
Ladder Logic

Ladder Logic Symbols | PLC Programming in RSLogix 5000 Studio Allen Bradley

Ladder Logic is one of the most common PLC programming languages. The standards of the language are well documented by the International Electromechanical Commission (IEC) in the exhibit 61131-3. However, official documentation of the ladder logic symbols isn’t easy to digest and doesn’t provide concrete examples of each one.Ladder Logic symbols are foundational elements that are memorized by every plc programmer. They’re essential to know if you plan to do any work with this PLC programming language.In this tutorial, we will discuss each symbol, the functionality it brings to the ladder logic plc programming language as well as illustrate two examples where they may be used.

Vladimir Romanov
April 9, 2020
Beginner
Ladder Logic

Groov EPIC | PAC Controller Setup and Input / Output Sequence Programming Tutorial

In our previous tutorial on the groov EPIC PAC Controller, we’ve unboxed the unit and looked at some of the basic hardware features. Today, our goal is to create a simple control sequence through the PAC Controller interface and demonstrate the interaction the controller can have with the field hardware.

Vladimir Romanov
April 9, 2020
Beginner
Opto 22 Groov Epic
PLC Instructions

Opto 22 Groov Epic PAC System Introduction Overview | SCADA Node Red MQTT

The Groov Epic by Opto 22 is hardware that combines the capabilities of a traditional PLC, modern features as well as state of the art software packages. In this introductory tutorial, we will take a first look at this controller, go over the hardware features, discuss the startup procedure and finally make a few comments about the software packages that are pre-installed on the controller.

Structured Text Logic and Boolean Instructions | Motor Starter Interview Practice

Structured Text PLC Programming handles logical and mathematical comparators similar to other programming languages such as C, C++, Java and Python. However, their syntax may be unfamiliar to those who work on PLCs within a ladder logic environment. That being said, every branch of PLC ladder logic is a state flow that can be simplified into a logical flow thus used in a single Structured Text statement.

Vladimir Romanov
April 9, 2020
Beginner
Structured Text
Interview Practice

How to download RSLogix 500, RSLogix 500 Emulate, and RSLinx for free.

Learn how to download RSLogix500, RSLogix500 Emulate, and RSLinx for FREE!

Vladimir Romanov
April 9, 2020
Beginner
Interview Practice

Introduction to Structured Text Programming in RSLogix and Studio 5000 Allen Bradley

Learn the basics of structured text, go over the fundamentals of the interface that are different from ladder logic and lastly build a few simple examples to illustrate an assignment of a variable.

Vladimir Romanov
April 9, 2020
Beginner
Structured Text
PLC Instructions

PLC Programming Fundamentals - XIC Instruction

The XIC, also known as Examine If Closed, instruction is one of the fundamental instructions used in ladder logic programming for Programmable Logic Controllers (PLCs). This instruction is always found on the left side of a ladder rung and will verify if the specified bit is in a logic HIGH state. If that’s the case, the instruction will evaluate to true and allow the rest of the rung to execute.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Fundamentals – XIO Instruction

The XIO, also known as Examine If Open, instruction perform the function opposite to the XIC (Examine if Closed). It’s a fundamental instruction for working with Programmable Logic Controllers (PLCs). This instruction can be found on the left side of a ladder logic rung and will evaluate to true if the specified bit is set to a LOW state. If that’s the case, the instruction will allow the rest of the rung to execute.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Intermediate Instructions – TON | Timer On

The TON, also known as Timer ON, an instruction is used to keep track of time of occurrence of certain events. The conditions preceding the TON instruction will allow the timer to start counting up to a specified value. Once this value is reached, the program will set specific internal bits notifying the programmer as well as other instructions within the PLC that the timer has finished counting. Furthermore, experienced developers can leverage the instruction to know when a certain process is being executed.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Intermediate Instructions – TOF | Timer Off

The TOF, also known as Timer OFF, an instruction is used to keep track of time of occurrence of certain events. The conditions preceding the TOF instruction will allow the timer to start counting up to a specified value. Unline the TON Instruction, TOF will start counting when the preceding conditions are FALSE. Once this value is reached, the program will set specific internal bits notifying the programmer as well as other instructions within the PLC that the timer has finished counting. Furthermore, experienced developers can leverage the instruction to know when a certain process is being executed.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Intermediate Instructions – RTO | Retentive Timer

The RTO, also know as Retentive Timer, an instruction is used to keep track of time just like the TON Instruction. However, there is a key difference between the two. The TON instruction will automatically reset the accumulated time upon a transition from HIGH to LOW. The RTO will simply “pause” the accumulated value during this transition. In other words, the timer will retain the value it currently has until it is energized again or forced to reset. Due to this capability, it’s an excellent tool for a process which may be interrupted but needs to keep track of a continuous event. For example, you can easily create a timer which would allow a certain valve to only open for a certain duration even though it is stopped in between.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Intermediate Instructions – CTU | Count Up

The CTU, also known as the Count Up, instruction is used in pair with a Counter construct to count the number of LOW to HIGH transitions of the preceding logic. The CTU instruction will increment the “Accum” value each time the logic which leads into it is set to TRUE. Unline the Timer Instruction, the CTU will not keep incrementing until the rung is set to LOW and comes back to being HIGH. This critical element of ladder logic programming allows a programmer to keep track of how many products have passed a certain sensor, how many revolutions have been made by a certain motor, how many times a certain alarm was set and so on. It’s a widely used instruction which is extremely versatile and easy to work with.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Intermediate Instructions – CTD | Count Down

The CTD, also known as the Count Down, instruction is used to decrement the value of the counter associated with it. This instruction will detect a FALSE to TRUE transition of the logic leading to it and decrease the “Accum” value of the counter by 1. The effect of using this instruction is the exact opposite of what the CTU Instruction does to the counter. Just like its counterpart, this instruction will be found in a rung which will count a certain number of events. Due to the fact that it decrements the value, the use cases need to be very specific in order to be clear to the next programmer.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Comparison Instructions – NEQ | Not Equal

The NEQ, also known as the Not Equal, instruction is used to compare two values just like the EQU Instruction. However, the key difference is that the NEQ will return TRUE if the values are not equal to each other. In other words, the outcome of this instruction is the absolute opposite of what the EQU will give us.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Comparison Instructions – EQU | Equal

The EQU, also known as the Equal, instruction is used to compare two values. The EQU instruction is an input instruction which will return TRUE if the two values within “Source A” and “Source B” fields are equal to each other. If that condition is met, the instruction will allow what’s on the right of it to execute. The EQU will compare the two values and only evaluate to true is the two integers are equal. Should they become unequal, the instruction will update on the next PLC scan.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Fundamentals – OSR Instruction

Learn about One-Shot Rising instructions for Allen-Bradley PLCs

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Fundamentals – OSF | One Shot Falling | Instruction

The OSF, also known as One Shot Falling, instruction allows a programmer to create a scenario where an output is energized for a single scan when a transition from a logic HIGH to a logic LOW is detected on the input side of the instruction. The instruction allows an experienced programmer to capture key components based on such a transition and allow a one-time execution of particular bits of logic. This instruction can be found on the right side of a ladder logic rung and has two bits tied into it. One of these bits, labeled as “Output Bit”, can be used elsewhere in the code to energize other instructions when the OSF is enabled.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Fundamentals – ONS Instruction

The ONS, also known as the One Shot, instruction will allow the rung to execute once if the data leading to it is true. The instruction will not let the rung to evaluate again until the input is set back to LOW and then HIGH. The One Shot instruction is extremely useful when you need to execute a certain instruction once. A common example would be saving initial parameters of a process when it’s initialized. The ONS is found on the input side of a ladder logic rung structure.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Fundamentals – OTU Instruction

The OTU, also known as Output Unlatch, instruction will set a bit to LOW if all the conditions leading to it evaluate to true. This instruction is one of the fundamental instructions for Programmable Logic Controllers (PLCs), but it should be used with caution. This instruction will be found on the right side within a ladder logic structure and turn a bit to a LOW state if the preceding instructions evaluate to true.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Fundamentals – OTL Instruction

The OTL, also known as the Output Latch, instruction will force a single bit of logic into a high state if all the conditions leading to it are true. It’s a basic instruction which is powerful but can cause programmers a lot of grief if used improperly or too frequently. This instruction is found on the right side of a ladder logic rung and will switch a bit to a HIGH state once it executes. Unlike the OTE Instruction, the OTL will never turn the bit LOW. In order to make that happen, you can leverage other instructions that accomplish exactly that. That being said, the most common pairing with an OTL is an OTU (Output Unlatch).

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Comparison Instructions – LES | Less Than

The LES, also known as the Less Than, is an instruction used to compare two values against each other. The instruction takes two integers, floats or constants and will return TRUE if the value specified in “Source A” is less than the one in “Source B”. The “Source B” operand must be strictly less than the one specified in “Source A”. In other words, the instruction will return FALSE if they are equal.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Comparison Instructions – GRT | Greater Than

The GRT, also known as the Greater Than, is an instruction that compares two operands and evaluates if the value stored in “Source A” is greater than the value stored in “Source B”. If that’s the case, the instruction will evaluate to TRUE and allow the rest of the rung to execute. The GRT instruction may take integers, floats or constants as operands.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Comparison Instructions – LIM | Limit Test

The LIM, also known as the Limit Test, is an instruction which will compare the specified operand to two limits: lower limit and high limit. Should the value be greater than the lower limit and less than the higher limit, the instruction will set the output to TRUE. However, if the opposite is the case, the instruction will evaluate to FALSE. Furthermore, the reversal of the two limits will have the opposite logic effect on the instruction effectively resulting in a NOT of the original instruction.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Fundamentals - How To Use BOOTP / DHCP Tool Set An IP Address Of a New Rockwell PLC

BOOTP / DHCP tool from Rockwell is a necessity when it comes to working with Programmable Logic Controllers (PLCs). However, it is a somewhat controversial tool as it still has a lot of bugs and quirks which frustrate even the most experienced programmers. In this article, we will be exploring the proper use of this tool as well as go over some of the common pitfalls for those who need to set an IP address of their PLC.

Vladimir Romanov
April 9, 2020
Beginner
PLC Hardware
Networking

PLC Programming Comparison Instructions – MEQ | Masked Equal

The MEQ, also known as the Masked Equals, is an instruction which will perform a similar function to the EQU (Equals) Instruction, with one key difference: a mask is applied to the compared bits. This instruction will take three operands: two which will be compared and a mask which needs to be applied. A mask is a key element of programming which boils down to selecting which bits need to be processed by the controller. In the case of the MEQ instruction, only the bits which have been masked as HIGH will be compared. Should those bits be the same within the two other operands, the instruction will evaluate to TRUE.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions

PLC Programming Computational Mathematical Instructions – ADD | Addition

The ADD, also known as the Addition, is an instruction which will perform a mathematical addition of two integers or floats. Performing an addition has a lot of uses in PLC programming. In addition to the obvious, it can be creatively used to create advanced functions such as step counters, average calculations and so on. The instruction takes three operands: two which will be added and one into which the result will be stored as the instruction executes.The ADD instruction is used all the time and is one of the most fundamental instructions of the Computational / Mathematical set. It’s something every programmer should be familiar with.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions

PLC Programming Computational Mathematical Instructions – SUB | Subtraction

The SUB, also known as the Subtraction, is an instruction which will perform a mathematical subtraction of two values which may be integers or floats. This instruction is used quite frequently in PLC programming and is one of the most fundamental mathematical operations. It can be used to calculate the difference between two sensor values, the deviation from a setpoint and much more. At its core, the instruction will evaluate the difference between the two values specified in “Source A” and “Source B” and store the resulting outcome in the “Dest” or the destination register.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Computational Mathematical Instructions – MUL | Multiply

The MUL, also known as the multiply, is an instruction which will perform a mathematical multiplication of two integers or floats. This mathematical instruction will be executed upon the registers specified in “Source A” and “Source B” and have the result stored within the register specified in the “Dest” field. This is a fundamental PLC instruction which is frequently used for scaling purposes. This need arises quite frequently when dealing with analog signals.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming Computational Mathematical Instructions – MOD | Modulo

The MOD, also known as the modulo, is an instruction which allows the user to calculate the remainder produced by a division of two integers. This instruction is not frequently used in ladder logic programming but is very useful for calculating the remainder of a ratio, production excess, and several other parameters. The instruction takes three registers as operands. The first two are the dividend and the divisor. The result is stored in this third register which is labeled as the destination.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

HMI / PLC Fundamentals - Linking Studio 5000 Tags to a PanelView Plus 1000 HMI Terminal Tutorial

Today, we will be covering the process of establishing a link between a PLC running v30.11 firmware and a PanelView Plus 1000 HMI Terminal running v5.10 firmware. This is a very important process in creating an HMI application and allows the engineer to control PLC-based tags from the HMI terminal.

Vladimir Romanov
April 9, 2020
Beginner
HMI Development
PLC External Hardware

PLC Interview Questions - Building a 2 Button Motor Starter System

There is a number of scenarios one can create to test PLC Programmers. One of the most simple, yet challenging for a beginner, questions is the famous motor starter. A simple system which utilizes two buttons and an output stumbles those who’ve little to no experience with PLCs. Furthermore, this question will reveal if the candidate asks the right questions, makes the correct assumptions and is able to reason through a simple assignment presented to him.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Interview Practice

PLC Programming Fundamentals – OTE Instruction

The OTE, also known as Output Energize, instruction will energize a single bit of data if the input leading to it is true. It’s a fundamental instruction used in Programmable Logic Controllers (PLCs). This instruction will be found on the right side within a ladder logic structure and turn a bit to a HIGH state if the preceding instructions evaluate to true. If the same instructions evaluate to false, the OTE instruction will set the specified bit to a LOW state.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Programming - Getting Started in RSLogix 500 & MicroLogix 1100 Programmable Logic Controller

Getting into Programmable Logic Controller (PLC) Programming can be stressful for a beginner. There aren’t many guides on how to get started and such guides are often convoluted and too complicated for a complete beginner.In this article, we will be exploring how you can get up and going in RSLogix 500 on a MicroLogix 1100 PLC. The reason for this software & hardware combination is that it offers a cost-effective way to get onto a robust platform which is used in many manufacturing facilities today. RSLogix 500 offers a free version of the software which can be used to practice most of the instructions used in most PLC platforms. A MicroLogix 1100 PLC is a legacy piece of hardware which can be purchased on eBay from 200$; extremely inexpensive for a PLC. Check out the PLC purchase guide here.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

Which PLC Hardware to Buy, When to Invest & What You Should Know before Purchasing PLCs

Learning different platforms can be very exciting. However, as the excitement diminishes and we get to some of the most difficult concepts, it could be tempting to switch platforms, purchase new hardware or to spend time elsewhere. This is the reality a lot of us have faced or will face at one point or another.

Vladimir Romanov
April 9, 2020
Beginner
PLC Hardware
PLC External Hardware

PLC ControlLogix Hardware | Allen Bradley ControlLogix Hardware Training | Chassis, Power Supply

Understanding the Hardware is the first step of working with Programmable Logic Controllers (PLCs). In this tutorial, we will be going over the entire ControlLogix platform which is the flagship product from Rockwell Automation.ControlLogix is classified as a large control system which is typically used in plant-wide applications. This platform allows PLC Programmers to have full control over various local and remote systems. ControlLogix hardware is critical in many facilities and provides a level of flexibility, unlike any other PLCs. Furthermore, it has the most memory and fastest speed available when compared to other systems from Allen Bradley.

Vladimir Romanov
April 9, 2020
Beginner
PLC Hardware
Troubleshooting

PLC Programming Tutorial | Allen Bradley Training in RSLogix 5000 Ladder Logic Basics for Beginners

PLC Programming is a highly desired skill in industrial automation. It’s what allows one to create a set of instructions in order to control different devices, pieces of machinery and entire manufacturing plants. However, there are multiple challenges when it comes to learning PLC programming: high complexity of the platforms, costly hardware & software costs as well as low availability of online materials.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Interview Practice

Industrial Relay Control System | Wiring a 24 Vold DC Relay Circuit

Industrial Relays have been used in Automation for decades. These fundamental building blocks of electrical circuits allowed the first automated systems to function without the need of modern PLCs and computers. Although you won’t find any relay based logic circuitry today, they still play an important role in modern control systems.

Vladimir Romanov
April 9, 2020
Beginner
PLC External Hardware
Troubleshooting

RSLogix Studio 5000 JSR JMP LBL Instruction | Navigating Routines PLC Programming Jump Control

PLC programs are executed sequentially. In other words, the PLC executes a rung before proceeding to the next one. Within a single rung, the PLC will execute each sub-branch before proceeding to the next one. A PLC programmer may choose to navigate between rungs in a non-sequential order as defined by the routine. In other words, using instructions such as JSR, JMP and LBL allows one to create an order which doesn’t follow the rung labels.

Vladimir Romanov
April 9, 2020
Beginner
PLC Instructions
Troubleshooting

PLC Networking Basics Tutorial | RSLinx Classic Lite EtherNet/IP Driver Configuration User Training

Programmable Logic Controllers are placed at the heart of the manufacturing process. If they’re the heart, the veins which link them to other field components are the network. Deploying a control systems network can be challenging & without proper tracking and implementation may lead to complications.A young organization may choose to track their network infrastructure through a simple Excel spreadsheet. This method is prone to errors on larger scales, but it very easy to manage and visualize for small networks. I manage a private home network of over 20 devices through Excel.

Vladimir Romanov
April 9, 2020
Beginner
Troubleshooting
PLC External Hardware

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