Programming Logic Controllers Overview Chapter 1 PLC Use

Programming Logic Controllers Overview - Chapter 1

PLC Use • • Machine control Process control Motion control Batch control Diagnostic Other Usually Multiple applications

History and Development • 1960’s • “Five hours to find it, five minutes to fix it”

History • Richard Morley – Modicon • • First PLC ladder logic programming • Odo Josef Struger • Allen-Bradley

History and Development • • • http: //en. wikipedia. org/wiki/Programmable_logic_controller http: //en. wikibooks. org/wiki/Introductory_PLC_Programming http: //www. isa. org/Content. Groups/News/2006/February 24/His tory_of_the_PLC. htm http: //www. barn. org/FILES/historyofplc. html http: //www. control. lth. se/media/Education/Doctorate. Program/2012/Hi story. Of. Control/Vanessa_Alfred_report. pdf http: //www. plcs. net/chapters/history 2. htm

Block Diagram

Block Diagram

Block Diagram

Central Processing Unit • • http: //en. wikipedia. org/wiki/Central_processing_unit A central processing unit (CPU) is the hardware that carries out the instructions of a computer program by performing the basic arithmetical, logical, and input/output operations of the system.

Memory Devices • RAM • ROM • • ROM Programmable ROM (PROM) Erasable programmable ROM (EPROM or UVEPROM) Electrically Erasable ROM (EEPROM) • Static RAM • Dynamic RAM

Address Decoder Unit • Address to circuit • Binary number to path

Binary • http: //www. jodyculkin. com/category/comics-2/countingbinary Decimal pattern Binary numbers 0 0 1 1 2 10 3 11 4 100 5 101 6 110 7 111 8 1000 9 1001

Transisters and Gates • http: //hyperphysics. phy-astr. gsu. edu/hbase/electronic/trangate. html • http: //www. cs. bu. edu/~best/courses/modules/Transistors 2 Gates/ • http: //www. cs. bu. edu/~best/courses/cs 101/F 95/lectures/From. Gates. To. Adder. html • http: //www. electronics-tutorials. ws/logic_10. html

Peripheral Chips • Buffers • Data conversion • Networking • Voice Recognition • more

Discrete Input Modules • Discrete means enumerable, countable, not continuous but distinct • Digital not analog • Real numbers are not discreet • Between 1. 0 and 2. 0 we have 1. 50. • Always a number between x and y • Integers are discrete. No number falls between 1 and 2 • Generally • • On or Off 1 or 0 True or False Closed or Open

Discrete Output Modules • Set to on/off • Set to true/false • Set to 1/0

Analog Input/Output Devices • Analog is a continuous signal (wave) • Set to varying voltage levels • Inputs converted to digital via analog to • digital converter logic Digital to analog conversion occurs for outputs

PLC Power Supply • Battery backup • Capacacitor allows battery exchange

Allen-Bradley Programmable Logic Controllers • • PICO Micro. Logix Small Logix SLC 500 Series • LAN and WAN capabilities • PLC-5 • May have thousands of I/0 ports