PROGRAMMABLE LOGIC CONTROLLER
- 1. PLC Presented by NAME : S.ARUNKUMAR YEAR : IV YEAR DEPARTMENT : MECHANICAL ENGINEERING COLLEGE : SUDHARASAN ENGG COLLEGE
- 2. WHAT IS PROGRAMMABLE LOGIC CONTROLLER ? A programmable Logic Controller (PLC)is defined as a digital electronic device that uses a programmable memory to store instructions and to implement functions such as logic, sequencing, timing, counting and arithmetic in order to control machines and processes,
- 3. ARCHITECTURE OF A PLC :
- 4. A PLC CONSISTS OF, (i) CPU (CENTRAL PROCESSING UNIT) (ii) MEMORY (iii) I/O PROCESSING DEVICES
- 5. (i) CENTRAL PROCESSING UNIT: A central processing unit ,also called a central processor or main processor ,is the electronic circutory within the computer that carries out the instructions of a computer program by performing the basic arithmetic ,logic, controlling ,and input/output operations specified by the instructions. • The arithmetic logic unit (ALU), which performs arithmetic operations like addition and subtraction and logical operations like AND, OR,NOT and EX-OR etc. • The control unit (CU), which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.
- 6. • The arithmetic logic unit (ALU), which performs arithmetic operations like addition and subtraction and logical operations like AND, OR,NOT and EX-OR etc. • The control unit (CU), which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.
- 7. FUNCTIONS OF CPU : It consists of Fetch, Decode, Execute, Store.
- 8. Fetch: Each instruction is stored in memory and has its own address. The processor takes this address number from the program counter, which is responsible for tracking which instructions the CPU should execute next. Decode: All programs to be executed are translated to into Assembly instructions. Assembly code must be decoded into binary instructions, which are understandable to your CPU. This step is called decoding.
- 9. Execute: While executing instructions the CPU can do one of three things: Do calculations with its ALU, move data from one memory location to another, or jump to a different address. Store: The CPU must give feedback after executing an instruction, and the output data is written to the memo
- 10. BUSES : A bus is defined as a set of physical connections which can be shared by multiple hardware components in order to communicate with one another .All computers have four fundamental buses: Data buses ,Address buses, Control buses and System buses . 1) DATA BUSES, 2) ADDRESS BUSES, 3) CONTROL BUSES, 4) SYSTEM BUSES
- 11. (ii) MEMORY • Memory devices are where the program are started in the controller or some groups of binary digits of 1s and 0s stored in the form of bytes at individual locations identified by their addressed. • The functions of memory sectors to store the status of inputs and outputs. • The sectors to store systems informations such as scan time ,fault status ,fault codes and watchdog timers .
- 12. There are several memory elements in PLC systems : 1) RANDOM ACCESS MEMORY (RAM) 2) READ ONLY MEMORY (ROM)
- 13. 1) RANDOM ACCESS MEMORY : RAM (Random Access Memory) is the hardware in a computing device where the operating system (OS), application programs and data in current use are kept so they can be quickly reached by the device's processor . 2) READ ONLY MEMORY(ROM): • It is a type of storage medium that permanently stores data on personal computers (PCs) and other electronic devices. • It contains the programming needed to start a PC, which is essential for boot-up; it performs major input/output tasks and holds programs or software instructions.
- 14. (iii) I/O PROCESSING DEVICES : The input and output unit provides the interface between the system and the outside world and allowing connections to be made through input/output channels to input devices such as sensors and output devices such as motor and solenoids.
- 15. THANK YOU