Optical isolation protects the backplane circuits by isolating logic circuits from input signals. The designing, programing, testing, commissioning, troubleshooting, and maintenance of control logic are much easier using the ladder logic programs in a plc than in hardwired circuit. This site is not directly affiliated with business industrial network. Examine the following illustration of a simple batteryswitchlamp circuit, connected together using screwterminal blocks, each connection point on each terminal block identified by a unique number. If the customer does not have one to relate, one must be found by testing the units performance. The program takes the place of much of the external wiring that would be required for control of a process. They can provide valuable information about the wiring, and inputoutput io modules within the unit. No patent liability is assumed with respect to use of information, circuits, illustrations, equipment, or software described in this text. Plc troubleshooting can be performed in many different ways and as the. Electrical troubleshooting, plc troubleshooting training. Problem description in some conveying system operator. This is a basic course, without any prerequisites, that. The tstrainer is designed to assist industrial electrical contractors, industrial maintenance, technicians, apprentices and other students with systematic.
Basic troubleshooting strategies all about circuits. Design a plc program and prepare a typical io connection diagram and ladder logic. Plc program for latching and unlatching circuit plc latching and unlatching circuit this is plc program for latching and unlatched circuit for output. Learn and determine the operation of plc circuits using ladder diagrams, wiring diagrams, inputoutput schematics, and data sheets.
A machine stopped working on me today whats happening is that a dosing unit isnt getting a signal to run there is a proxy sensor which detects cans and when it sees a can it is supposed to start the filling and no can then no fill. Troubleshooting and using circuit laws gaining circuit familiarity troubleshooting basics common troubleshooting techniques the program the practical troubleshooting of electronic circuits workshop will teach you how to recognise and efficiently troubleshoot common electronic component and circuit problems. Troubleshooting plc controls, circuits with plc simulator see more. A plc is a complete system, probably using many chips, so its larger, more expensive, and not as versatile as you are limited to what the designer included. An output circuit controls the output signal in the following manner. Troubleshooting control circuits control circuits are generally designed so that an individual circuit controls only one function of a particular process or machine. New parametersetting dialogues reduce setup time, and with standard function blocks in iec 61. If the current is less than 22ma and the supply output voltage is low, then the power supply could be faulty.
Advantages of a plc control system easier to troubleshoot. Practical troubleshooting of electrical equipment and control. The opposition to current flow in this type of ac circuit is made up of three components. The electrical troubleshooting examples may help sharpen your electrical installation testing skills. In general, the plc will scan from left to right, top to bottom. After successful completion, the troubleshooter can improve their understanding of dc, ac, three phase circuits, relays, contactors, plc, electronics, and other related technology. In this module, your professionals will diagnose and repair over 60 faults in each of three simulated circuits containing plc controls. This programmable logic controller training simulates real world faults allowing user to use simulated vom, ladder logic and other tools to troubleshooting control circuits wired to the plc controller simulator. Automation systems troubleshooting has in general the same tactic in order to find the solution of systems fault. Troubleshooting plcs can be started by checking the healthiness status of cpu, io modules, fuse blowout and different plc failure reasons including wiring, field transmitters healthiness status or transmitter configuration.
Practical troubleshooting of electrical equipment and control circuits by mark brown, jawahar rawtani, dinesh patil there is a large gap between what you learn in college and the practical knowhow demanded in the working environment, running and maintaining electrical equipment and control circuits. Practice again and again is the solution in my opinion. Block diagram of programmable logic controller plc. Inputs pb2 figure 734 ladder logic program res output rto. At some point you will find one or more relays that have to be activated for it all to work and if they get their power directly from the plc outputs then you have to look at all the plc inputs that have say in things.
This software package will introduce the trainee to a proven system of troubleshooting. Look for improper voltages, improper waveforms, obvious component overheating. Plc troubleshooting and diagnostics machine tool help. The plc troubleshooting training with plc maintenance. Lets develop our procedure for troubleshooting an open circuit in the control circuit. Upon completion the technician will display skills in methodical. Theory and implementation programmable controllers an industrial text company publication atlanta georgia usa second edition l.
Safe and effective troubleshooting of electrical systems is an essential skill for maintenance technicians in industrial, utility, or commercial settings. Introduction to programmable logic controllers plc s industrial control systems fall 2006. The output circuits cannot detect shorted or open output points. The first step in plc troubleshooting is to decide if the problem is internal to the processor or in the io system.
Open circuit faults an open circuit fault is any fault that stops the operation of a machine due to an open wire or component. Hardware troubleshooting verify per installation manuals. However, the controller circuits we devised for these two situations would. Oct 14, 2011 troubleshooting plc circuits simutech multimedia. Control circuits are generally designed so that an individual circuit controls only one function of a particular process or machine. Lecture introduction to plcs mme 486 fall 2006 4 of 47 programmable logic controller a programmable logic controller plc is a specialized computer used to control machines and process. Basic logic gate troubleshooting worksheet digital circuits. Locating faulty components, identifying power quality problems, and troubleshooting circuits are just a few of the issues the maintenance technician may be confronted with when repairing.
For loose cables such as ones in a cable tray maintain a minimum of 6 inches between input power, output power and the controls, unless they have their own grounding shield such a metal conduit. Photo by rob ellis when handling auto repairs, you may feel overwhelmed and lost. Troubleshooting plc transistor output electronics forum. Parallel rlc circuit and rlc parallel circuit analysis. An input filter removes false signals due to contact bounce or electrical interference. The problem could be in the chandeliers wiring open wire connection, open connection in socket, or in the bulb itself burnedout filament. Isolating portions of the circuit is a good way to identify the area of concern. If a problem should occur, the first step in the troubleshooting procedure is to identify the problem and its source. Troubleshooting plc circuits troubleshooting plc circuits tplc is the fourth in our series of simulationbased training modules. How to do electrical troubleshooting of electrical motor. Ladder diagram example a manual mixing operation is to be automated using sequential process control methods. Identify where the plc problem might be with certain inputs or outputs etc. At this post i will give some basic instructions which are from my personal experience in order to give you a guide for how troubleshooting in automation systems plc dcs is.
Understanding electricity and how to troubleshoot a circuit. Question 1 a chandelier has five light bulbs in it, and one of them is not working. Plc input and output troubleshooting all about circuits. Fortunately, electrical circuit troubleshooting is an activity that works well for small groups of students to engage in as well as individual students.
All trademarks, registered trademarks, product names and company names or logos mentioned herein are the property of their respective owners. Plc basics and troubleshooting plc basics and troubleshooting course. At the completion of the course the students take the pmmi plc level 1 certificate. We will add more posts soon on many topics such as how to build a solar generator, and this post will help build the basics on which those posts will expand. The electrical problems start with basic electrical wiring, move up to plc examples. Notes on voltage range to expect when testing plc logic circuits. Hardware troubleshooting tips for troubleshooting control system if installation and startup procedures were followed closely, controller will give reliable service. Most plcs incorporate light emitting diodes leds in their design, which offer a good source of diagnostics. Two examples are explained on racing conditions in the plc. Lecture introduction to plc s mme 486 fall 2006 9 of 47. The included 32 page electrical troubleshooting pdf lab manual also provides more introduction to troubleshooting control circuits. Faulty cpu the best way to check for a faulty plc is to substitute a known good one to see if this corrects the problem.
Follow our 11 major steps in selecting a plc for an application and avoid using the wrong controller install sinking and sourcing inputs and outputs properlyone wrong wire and it wont work implement safety circuits correctly in plc applications to protect people and equipment. X l x c and r with the combination of these three values giving the circuits impedance, z. Perfect your plc circuit troubleshooting process by troubleshooting more than 60 faults in a safe training environment. Logic probes are useful tools for troubleshooting digital logic gate circuits, but they certainly have limitations. Circuits hands on write plc program and troubleshoot. Problem description in some conveying system operator fills tank manually by operation water pump manually. If there has been a major power surge, it is possible the plc internal power supply has been damaged. Sample pages from the workbook imagine having the answers to over 800 plc problems at your fingertips. The skills of the competent technician must include a methodical means of troubleshooting and root cause analysis. A plc is a solidstate, electronic device that controls the operation of a machine. Troubleshooting a 420ma loop page 3 of 4 power supply, malfunctioning electronics, etc arent part of troubleshooting a 420ma loop, unless the loop is being powered by a supply that is part of the indicator and one can continue by repairing the indicator to resolve these issues. Troubleshooting an open circuit faults in the control circuit.
Troubleshooting industrial controls training system. Electrical troubleshooting 1 before using a voltmeter on electrical components, do the following. Ch 10 sensors, safety, analog and troubleshooting 1 chapter 10 sensors, safety, analog and troubleshooting we now look outside the control panel at devices and methods of design that affect the design of the plc and the overall project. Lecture introduction to plcs mme 486 fall 2006 6 of 47 advantages of a plc control system eliminates much of the hard wiring that was associated with conventional relay control circuits.
The plc will update only at the end of the program logic. Troubleshooting plc circuits by testing thumbwheel switches, december 1995, p. The lab manual can be accessed via the software and you can also optionally print it. The symptom should automatically lead to the method of troubleshooting. Electrical motor control circuits is a product developed by business industrial network. The circuit also will not allow the operator to tie. Understanding basic electricity can be invaluable in both safety, as well as when troubleshooting and repairing an electrical circuit. If the field device connected to an input module doesnt seem to turn on, a problem may exist somewhere between the line connection and the terminal connection to the module. Maintenance troubleshooting industrial controls training system. This will permit you to manually activate the field device. These manuals are specifically made up for the individual panel, and are generally sufficient for any or all problems which may be encountered.
It also includes instructions on how to use the tstrainer. The technology inherent in the programmable logic controller plc eliminates the requirement for electromechanical devices such as control relays and timers and allows for exact operation of the preprogrammed formulas through electronic circuits, timers and counters. The removable connectors on the dl105 make this relatively easy. Actual outputs and inputs are not read until the end of the scan of the plc. Basic circuit troubleshooting worksheet all about circuits. Insufficient pilot pressure if dual stage valve check pilot and drain configuration. Determine whether or not voltage should be present between the following pairs of terminal block. We know from above that the voltage has the same amplitude and phase in all the components of a parallel rlc circuit. Mar 07, 2015 this is usually a case of not understanding how the plc scans logic. It uses a programmable memory to store instructions and specific functions that include onoff control, timing. More extensive troubleshooting is now required within the identified faulty unit.
At the completion of the course the students take the pmmi plc level 1 certificate test. If that pulls in its working then follow the power circuit to that coil to find what activated it and so on. Ladder logic ladder diagrams ladder diagrams are specialized schematics commonly used to document industrial control logic systems. Instructor will create issues and students need to diagnose and resolve the problem. If you need to maintain and troubleshoot plc systems, this exciting new program will help you understand how plcs work and provide you. This workbook provides not only valuable summaries of each of the text. At 334 pages, its the perfect companion to programmable controllers. We have discussed the ladder logic instructions before and looked at the simple ladder logic programs in chapter 2. Troubleshooting common electrical problems for industrial. To minimize the risk of potential safety problems, you should follow all applicable local, state and national codes that regulate the installation and.
It uses logic functions, which are programmed into its memory, via programming software. Basic troubleshooting strategies basic electricity pdf version. Cxprogrammer, the programming software for all omrons plc series, is fully integrated into the cxone software suite. For instance, in this simple circuit, a logic probe will give correct high and low readings at test point 1 tp1, but it will always read low even when the led is on at test point 2 tp2. Any supplement and comments are welcome how to troubleshoot a plc system. Electrical motor control circuits free download for windows. Basic circuit troubleshooting worksheet basic electricity. First place the plc in standby mode so the output isnt activated. In this module, your professionals will diagnose and repair over 60 faults in each of three simulated circuits containing plc. Programmable logic controller 1, a program stored in the central unit of a. Introduction to programmable logic controllers plcs. Troubleshooting plc circuits training software troubleshooting plc circuits uses a plc simulator to teach troubleshooting electrical circuits and the plc. Cxprogrammer includes a wide variety of features to speed up the development of your plc program. Handson experience with live circuits without the risk.
The ability to evaluate a students troubleshooting skills based on trouble shooting. For more information, refer to the holt cat electrical safety. Troubleshooting input modules an input circuit responds to an input signal in the following manner. They are called ladder diagrams because they resemble a ladder, with two vertical rails supply power and as many rungs horizontal lines as there are control circuits to represent. Siemens simatic s7 manuals and guides southern plcs. Problems with transmitters usually occur because of wiring. Troubleshooting a plc motor starter with jogging circuit. It seems to be natural to assume that most malfunctions of plc systems are due to processor problems, but in fact the opposite is true. Chapter 10 sensors, safety, analog and troubleshooting. Electrical troubleshooting of a relay control circuit. The internal operation of a plc can be monitored via a handheld programmer, terminal, or personal computer, and many indicator lights are provided for io troubleshooting. Plc troubleshooting and diagnostics programmable logic controllers problems plc learn how to troubleshoot and diagnose plc s with this procedure and how to identify the plc problem areas. These circuits contain plc cpu, digital input module, digital output modules, dc power supplies, relays.
Troubleshooting plc circuits tplc is the fourth in our series of simulationbased training modules. A virtual troubleshooting exercise such as this one is a good way to start students thinking in the right ways to becoming effective troubleshooters. This plc simulator used for plc training creates faults for user to learn skill of troubleshooting plc controls. The plc has following basic sections are, processor section cpu the processor section is brain of plc which consists of ram, rom, logic solver and user memory. Electrical motor control circuits free download for. The programmable logic controller plc was invented in the 1960s to replace the sequential relay circuits traditionally used in machine control.
The output bitswords are available to the inputs of the next rung of logic. If this is your case, you need to learn more about auto repairs. Implement a safe circuit with hardware and software interlocking. This section of plc programming covers problems in industrial automation. Conduct a hazard assessment and follow approved safe work practices. Troubleshooting plc circuits training software troubleshooting plc circuits uses a plc simulator to teach troubleshooting electrical circuits and the plc control. Included in this chapter are sensors, a separate study of safety. At the end is just an example how our software uses realworld workorder system to track student while doing electrical troubleshooting with our. Having an effective troubleshooting plan and following it can help obtain this feeling of satisfaction.
The following is a short discussion concerning basic electrical troubleshooting. For instance, if a set is dead, you should start by checking power input to. Troubleshooting an open circuit faults in the control. The block diagram of programming logic controller plc is shown in above figure. Use insulated gloves, tools, blankets, and barriers if required. About 70% of the time is spent working, handson, at a troubleshooting station with motor control circuits operating at a safe, low level of 24 volts. A programmable logic controller plc is a specialized computer used. Electrical troubleshooter for acdc circuits, relays, contactors and plcs photo credit. The best knowledge is obtained through practice and actual troubleshooting conditions. Plc latching and unlatching circuit this is plc program for latching and unlatched circuit for output. The intent of this article is to cover only the basics of plc troubleshooting, so there are some limitations on what will be discussed. Wear appropriate protective clothing and equipment.