PLCs: PROGRAMMABLE LOGIC CONTROLLERS
COURSE 520: 3 DAYS
Programmable logic controllers are commonplace in all areas of industry. Accordingly it becomes ever-more important that maintenance personnel should be able to carry out effective maintenance tasks on these systems.
PARTICIPANTS
This course will be invaluable to anyone involved in the maintenance of control systems which incorporate PLCs. Participants should ideally have an understanding of electrical principles.
COURSE PRESENTATION
The emphasis throughout is on useful, practical skills and their application in the context of common industrial situations. Much of the course is given over to ‘hands-on’ experience and the maintenance skills that are required when working with PLCs. Comprehensive course notes are provided. The various main PLC manufacturers are represented on the course - Allen Bradley, Siemens, Mitsubishi and others. Candidates gain experience of each of these types, and this generic knowledge prepares them to deal with any type of PLC in the future (providing that sufficient help or further training is provided).
COURSE OBJECTIVES
On completion of the course, participants will be able to
- understand the safety issues involved with PLCs and appreciate the need for safe working practices
- understand how PLCs are incorporated into modern industrial control systems, and the typical applications they are put to
- understand the logic functions performed by basic PLC instructions
- understand the methods of addressing inputs and outputs of PLCs
- understand the various methods of transmitting signals to and from PLCs
- identify the range of I/O modules available
- understand the use of battery back-up and ROM
- interpret ladder diagrams, statement lists and control system flowcharts
- use hand-held programmers and personal computers to interrogate PLCs
- monitor I/O lines to determine correct operation
- safely modify program parameters to solve process problems
- safely use I/O forces as an aid to fault-finding
- carry out fault-finding on PLC-controlled systems
- use systematic methods of fault-finding using specially designed flowcharts
- back-up programs and restore them back to PLCs.
Successful completion of the course leads to the award of Amicus / Technical Training
Solutions competence certificate 520: Programmable Logic Controllers.
What do candidates on the plc maintenance course actually do?
Candidates on the plc (programmable logic controllers) maintenance course begin by learning about the programming languages used with plcs and the typical aplications they are put to. They then look at the various expansion modules, wiring and connections typically found. This is all done without getting involved in the internal plc architecture, boolean logic principles or number system theories: We don't feel that these subjects are appropriate to candidates who are learning about maintenance of plc systems.
A few of the early pages from the course notes give an indication of this approach:
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We then introduce our specially-designed industrial simulators which incorporate conveyors, motors, solenoids and industrial sensors to engage the candidates in the complex control issues dealt with by industrial plcs:
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Candidates are then presented with a range of pre-programmed plcs. These employ complex industrial-style programs. Examples of some of the programs are shown here, extracted from the plc course notes:
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The plcs used on the course are shown below:
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Candidates then use PCs running real versions of each manufacurer's software to communicate with our plcs.
We use a range of software:
» Allen Bradley (Rockwell) RS-Logix
» Mitsubishi FX-GP Win
» Siemens Step 7
» Siemens Step 5
» Modicon PL707
Candidates have to get familiar with at least three of these software packages during the course:
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We also expect candidates to get familiar with at least one handheld programming unit during the course:
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Candidates can, of course, concentrate on using the pc software and handheld devices appropriate to them. We feel that experiencing various manufacturer's plcs and software provides a much more holistic understanding of plcs than a single-platform approach (using plcs and software from only one manufacturer, for instance).
The course incorporates fault-finding exercises, where we can simulate broken sensors, field wiring faults, power supply faults, plc input module faults and plc output module faults. Candidates are guided through a systematic method of finding faults on plc-controlled systems, using our specially-designed fault-finding flowchart:
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Safety issues are, of course, paramount considerations, and the dangers of applying output forces, modifying the values of timers and counters, the dangers of electric shock whilst working 'live' and making measurements, as well as the physical dangers associated with unexpected movement of the controlled system are all covered on the course.
The clear distinction that this course is about maintenance and not about programming also helps to make it clear to candidates that they should not be interfering with the program held inside the plc - a major safety consideration in many industries.
Candidates who complete this course are in a good position to advance to the plc programming course (if appropriate to them) or on to a more challenging manufacturer-specific course (if necessary).