BTEC National NQF Level 3 The machines automation, conveyor lines and process control has resulted in the ever rising steadiness of quality, velocity and cost savings within the complicated processes. The users have come to guess the high standards of quality in the goods manufactured that they use, but to an engineer these are the faces up to that build the profession motivating.
This unit will reflect on PLCs (programmable logic controllers), the control devices which help the automation of these processes. The PLCs capabilities have built up over the years, with the reliability, performance, and operational flexibility being the main attributes to their sustained success. In order to reach automated control and monitoring, these devices can be utilized on their own or in combination with others throughout systems/links of communication, which are themselves becoming more flexible.
The unit will establish learners to the applications and use of PLCs, the software and hardware that build up a PLC and the relations required between the component parts. The learners will build up their capability to use the techniques of programming to generate programs for modern PLCs. They will also increase an accepting of the diverse types media of communication utilized to connect the larger numbers of PLCs together, the architecture of networking utilized and the related protocols and standards.
The learning results once completion of this unit a learner should:
1. Know the selection of requirements hardware and software of a programmable controller.
2. Be capable to utilize the techniques of programming to generate a program for a modern programmable controller
3. Realize complicated applications of programmable controller
4. Understand the media and networks of data communications applied with modern programmable controllers.
Unit content of Programmable Logic Controllers Selection and Applications
1. Know the selection of requirements hardware and software of a programmable controller.
• The selection of Programmable controller: these criteria’s e.g. versatility and scanning time, cost;
Architecture of internal e.g. CPU (central processing unit), ALU (arithmetic and logic unit), flags, memory and types (volatile, non-volatile), registers;
Self-test, input/logic/output scans (Scan cycle);
• The system requirements of hardware and software: the specification of manufacturers’ of input/output (I/O) digital and analogue units;
Power supply;
The utilization of operating system;
The configuration of inputs and outputs;
The systems number such as, hexadecimal, octal, binary, binary-coded decimal (BCD);
The devices of input/output;
The mechanical switch relays (electromechanical and solid state);
Transducers such as, flow, temperature, smart sensors, pressure, simple drives and motors.
2. Be capable to utilize the techniques of programming to generate a program for a modern programmable controller
• The technique of programming: such as, functional diagrams, ladder and logic diagrams, graphical programming languages, statement listing, sequential function charts (SFCs) mimic diagrams;
• Create, save and present program: HCI (human computer interface) such as, personal computer, handheld input pad, graphical touch screens, text; The use of the system software to write, edit, save, delete, restore, load/unload, create reports, search;
The use of the fault diagnostic indicators;
To print copies of program;
The storage such as memory organization, scanning, back-up copies, continuous updating, SCADA (supervisor control and data acquisition)
• The types of instruction: the production of program with relay, branch, bit, comparison, timer/counter, arithmetic instructions, logical;
The controller loops of proportional integral derivative (PID).
3. Realize complicated applications of programmable controller
• The documentation of program: the considerations of hardware (maintainability, operational, environmental);
The types of instruction; testing documentation such as the instructions of software debug, indicators of diagnostic, data monitors, force facilities, search; The complex applications of engineering such as process control, machine, conveyor.
• Programmable controller for health and safety: safe operational practices for personnel and with equipment such as the risk assessment of tools and equipment, JSA (job safety analysis), the practices of housekeeping for work areas, PPE (personal protective equipment), control of non-participants from areas; The standards of health and safety comply to local, national, international standards such as local safety agreements between employers and employees, HSE (Health and Safety Executive), regulations of Health and Safety at Work Act 1974 for the use of display monitors;
Avoiding operations of haphazard such as planning considerations, risk management, testing (usability, unit, component, acceptance), commissioning of scenarios what If.
4. Understand the media and networks of data communications applied with modern programmable controllers.
• The media of communication: features description, selection criteria, ranges of frequency, technology such as digital, analogue, wireless;
The types of media (cable such as coaxial, twisted pairs, shielded/unshielded, fiber-optic, operational lengths, categories; connector such as BNC (Bayone-Neill-Concelman), ST (straight tip), RJ-45 (registered jack), USB (universal serial bus) type A and type B; opto isolator such as phototransistor, photodiode, triacs, thyristors)
• Network: the architecture of network (distributed intelligence, fieldbus, opencommunications networks); The standards/protocols network such as ISO (International Organization for Standardization), FIP (Factory Instrumentation Protocol), IEEE (Institute of Electrical and Electronic Engineers), EIA–485 (Electronics Industry Association), and MAP (Manufacturing Automation Protocol).