1. Micro computer based process control
Programmable logic controller

2. CONTROL EQUIPMENT-Principles
Relay based system speed or resistance to electrical noise
DIGITAL LOGIC based
Computer based complex functions
PLC based

3. DIFFERENCE BETWEEN VARIOUS CONTROL EQUIPMENT
Operating speed
Physical size
Capacity for complicated operations
Ease of changing configuration
Electrical noise immunity
Installation
Ease of maintenance
Price for function

4. PLC-history`` 1970-Electro mechanical relays
1968-PLC-General motors company
1977-Microprocessor based plc
ALLEN BARDLEY –USA
8080Micro processor
256 Bytes to Mega bytes
PID
Feed forward etc

5. Advantages

7. PLC selection

8. PLC architecture Selectorswitch proximity, timer contact
Pilot light,horn,
timer

10. Architecture details Power supply I/O systems Real time CPU
Memory unit
Programmer unit
Peripheral devices-

11. Power supply
I/O Devices-
Bcd,thumblRTD, TC,Flowmeters,strain gauges,pushbuttons,limit switch,electromechanical relay,registers,bcd,thumbwheel etc
Output-pilot lights,solenoidvalves,annunciatorwindows,displays,

12. Programmer units:handheldunits,standalone crt units,pcs,
Peripheral devices:pc compatible software
Colur graphics,crt,

13. Basic structure

14. Plc programming
Ladder diagrams:

21. Ladder translation of plc programming

23. 6 rung Ldder diagram