1. PROGRAMMABLE LOGIC CONTROLLER

2. Control Systems Types  Programmable Logic Controllers  Distributed Control System  PC- Based Controls

3. PLC  The PLC is an assembly of solid state digital logic elements design to make logical decisions and provide outputs.  PLC is programmed interface between input sensor &output device.

4. Programmable Logic Controllers  Sequential logic solver  PID Calculations.  Advanced Subroutines  BIT Operations.  Data Transfer.  Text Handling.

5. Applications :  Machine controls, Packaging, Material handling, similar Sequential task as well as Process control Advantages of PLC :  They are fast and designed for the rugged industrial environment.  They are attractive on Cost-Per-Point Basis.  These Devices are less Proprietary ( E.g.. Using Open Bus Interface.)  These Systems are upgraded more Capabilities with dedicated PID and Ethernet Modules. Disadvantages of PLC :  PLC one time cost is high  To maximize PLC performance a number of IO Modules to be added.  PLC hold only one copy of program. Programmable Logic Controllers

6.  Central Processing Unit (CPU)  Input Modules  Output Modules  Power Supply  Bus system  Rack(Rail) P L C Components(Hardware) CPU POWER SUPPLY I/P mod O/P mod m

7.  It is a micro-controller based circuitry. The CPU consists of following blocks : Arithmetic Logic Unit (ALU), Program memory Process image memory (Internal memory of CPU) Internal timers,counters and Flags.  CPU performs the task necessary to fulfill the PLC functions. i.e. Scanning I/O bus traffic control, Program execution, Peripheral and External device communication, data handling and self diagnostics. Central Processing Unit

8.  These modules act as interface between real-time status of process variable and the CPU.  Analog input module : Typical input to these modules is  4-20 mA, 0-10 V  Ex : Pressure, Flow, Level Tx, RTD (Ohm), Thermocouple (mV)  Digital input module : Typical input to these modules is 24 V DC, 115 V AC, 230 V AC  Ex. : Switches, Pushbuttons, Relays, pump valve on off status Input module

9.  These modules act as link between the CPU and the output devices in the field.  Analog output module : Typical output from these modules is 4-20 mA, 0-10 V  Ex : Control Valve  Digital output module : Typical output from these modules is 24 V DC, 115 V AC, 230 V AC  Ex. : Solenoid Valves, lamps, Actuators, Pump valve on off control Output module

10. I/O MODULE SPECIFICATION  COST  INPUT VOLTAGE  ON-STATE INPUT VOLTAGE RANGE  AMBIENT TEMP RATING  INPUT DELAY –  NOMINAL OUTPUT VOLTAGE  MAX O/P CURRENT  ELECTRICAL ISOLATION –

11.  The power supply gives the voltage required for electronics module (I/O, CPU, memory unit) of the PLC from the line supply.  The power supply provides isolation necessary to protect the solid state devices from most high voltage line spikes.  As I/O is expanded, some PLC may require additional power supplies in order to maintain proper power levels. Power Supply

12.  It is path for the transmission of the signal between power supply module,processor and I/O modules.  The bus comprise of several single line i.e. wires /tracks Bus System

13. Advantage of PLC Over Relay RELAY PLC 1-More wiring 1-Less wiring 2-Changes difficult 2-Changes easy 3-More power 3-Low power 4-More maintenance 4-Solid state reliability 5-Difficult to expand 5 -Easy to expand

14. PLC Cycle Outputs CPU Inputs  Sense the Input  Process the Logic  Give Output

15. PLC Signal Flow Programming Terminal O:0/7 O:1/5 Output Devices Output Modules Processor MemoryInput Module Input Devices Ladder Program O:0/7 O:1/5 I:0/6 I:1/4 O:1/5 I:0/6 I:1/4 I:0/6 I:1/4 Data I/p Image Table Output Image Table

16. PLC Architecture Evolution u 1970s : Discrete Machine Control Programming Terminal PLC I/O Connection is Point to Point Programming Language : - Relay ladder logic - Flexibility in altering Control system operation Connection is Point to Point

17. u 1985 : Discrete and Process Control PLC Architecture Evolution Reasonable Computer Running PLC Programming Software PLC I/O Programming Language : - Ladder Program - PID - Data Storage MS - DOS

18. PLC Architecture Evolution u 1990’s : Discrete and Process Control PC running PLC Programming Software PLC I/O Connection in networked allowing Multiple PLC PLC became a part of the developing enterprise resource system Windows PLC

19. Today : Distributed I/O Modules Distributed I/O modules PLC Distributed I/O scanner Data Communication Bus PLC Architecture Evolution

20. Remote I/O Network SPLITTERS FIBER OPTIC LINK Remote I/O Today : Hot Redundant System PLC Architecture Evolution

21. Controller Workstation Switched Hub PLC Architecture Evolution Today : Ethernet Technology in PLCs

22. Remote Platform Wireless Modem PLC H M I Display PC PLC Architecture Evolution Today : Wireless communication PLC

23. PLC Systems of various vendors Siemens  S5 -110U, 115U, 135U  S7 - 200, 300, 400 Allen Bradley  Micrologix 1000, 1200, 1500  SLC 5/01, 5/02, 5/03  LOGIX PLATFORM Modicon  Nano  Micro  Premium  Quantum

24. 8 Analog Inputs 1 Analog Output Up/Down Fast Counter Up Counter Programming Terminal PC Connection Unitelway Port for connection of up to 5 Slaves PCMCIA memory expansion port PCMCIA communications port TSX37-22 Built in display for I/O (in-rack, AS-i) and Diag I/O Modules Configuration of PLC : Modicon

25. Configuration of PLC : Siemens CPU External Power Supply I/O Modules

26. Configuration of PLC : Allen Bradley CPU Power Supply I/O Modules

27. Configuration of PLC : GE FANUC CPU I/O Modules Back plane

28. PLC Programming Standards  Ladder Diagram  Function Block Diagram  Sequential Function Chart  Structured Text Language

29. Scan Rate  The completion of one cycle of the sequence is called- SCAN  Time required for one cycle is called SCAN TIME

30.  Cost of hardware,  I/O requirement  CPU memory  Spare parts& Maintenance,  Reliability,  Flexibility&  Integration of High-level Application.  Compatible Protocol PLC Selection Criteria

31. Memory Types  ROM (Read Only Memory)  RAM (Random Access Memory)  PROM (Programmable ROM)  EPROM (Erasable PROM)  EAROM- Electrically alterable ROM  EEPROM-Electrically erasable PROM

32. Binary System u BIT – Each digit of a binary number i.e.0 or1 u BYTE – Group of 8 bits u WORD = Two bytes=16 bits u DOUBLE WORD =Two word =4bytes=32bits 10234567 8 BIT WORD BYTE 16 BIT WORD

33. PLC : Terminology u INPUT is referred by – I u OUTPUT is referred by – Q or O u TIMER is referred by – T u FLAGS are referred by – M or B u COUNTERS are referred by – C

34. PLC : Protocol u It is a set of rules for data transmission when PLC is connected to network u RS-232 (Recommended standard) u RS-485 u MPI(Multi point Interface) u Profibus u DH(Data Highway) u Ethernate u Controlnet