programmable logic Controller intro.pptx
- 2. PLC(Programmable Logic Controller) Topics to be presented: What is PLC? Introduction to PLC Topology System and field devices Types of PLC Programming languages PLC scan cycle PLC programming concepts Ladder logic & Comparison of Relay logic and Ladder diagram PLC Hardware
- 3. What is PLC? PLC’s (Programmable logic controllers) are micro processor based computer devices that are designed to control machines and process automatically. Used in commercial and industrial applications A PLC monitor Inputs, make decisions based on its program given and control outputs to automate a process or machine
- 4. Slave Controller Main Controller External Power Supply Internal Power Supply Memory & programs I/P Field Device I/P Mod O/P Mod O/P Field Device Programming Device PLC boundary PLC Topology
- 5. Programming languages • The 5 most popular types of programming languages defined by the IEC 61131-3 standard are: Structured Text (ST) Sequential Function Charts (SFC) Ladder Logic Diagram (LAD) Function Block Diagram (FBD) Instruction List (IL)
- 7. PLC PROGRAMMING CONCEPTS • Totally acquainted with Relay logic system • It is essential to come to complete understanding of the requirements of the system to be controlled. • Determine the approximate number of inputs/outputs and memory required to accomplish the task. • System should be fail-safe design • Adjust your program with different languages i.e STL/LAD/FBD according to the software supplied by the manufacturer. • Complete the documentation process
- 8. What is Ladder logic? • Ladder logic(LAD)/Ladder diagram is one programming language used with PLC’s. • Ladder logic uses components that resemble elements used in line diagram format to describe hard wired control. • It has two vertical rails(supply power) and as many rungs(horizontal lines or networks) as there are control circuits to represent, looks like:
- 9. Comparison of Relay logic and Ladder diagram I0.1 M INPUT SIDE (FIELD DEVICES+I/P MOD) L 1 L 2 L 1 L 2 O/P SIDE( FIELD CONTACTOR + O/P Mod I/P device I/P module CPU Program I0.1 Q0.0 Q0.0 O/P mod
- 10. Network-1 Network-2 I 0.0 I0.1 Q0.0 Output element I0.4 I0.5 Q0.1 Ladder diagrams components I= Input Q= output Digits=bits
- 11. PLC Hardware Input module CPU Central Processing Unit Output module Programming Device Operator Interface Interfacing Module
Editor's Notes
- #6: IEC stands for International Electro technical Commission depending on the PLC platform of choice, specific languages may come at a premium or not be available at all. For example, only the full license of RSLogix 5000 will have access to languages beyond Ladder Logic.