Mechatronics MECH 1340 Digital Fundamentals & PLCs Introduction

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1 Mechatronics MECH 1340 Digital Fundamentals & PLCs Introduction Khalid Tantawi Department of Career Readiness Mechatronics 5004 Motlow College Blvd, Room # 214 Smyrna, TN Note: All pictures in this presentation are in the public domain, and taken from Wikimedia Commons 1/14/2019 1

Introduction A Programmable Logic Controllers (PLC) is

programmed to control processes of different levels of

2 Introduction A Programmable Logic Controllers (PLC) is an industrial computer that is capable of being programmed to control processes of different levels of complexity, and is designed to sustain the industrial environment. PLCs were initially designed to replace the conventional hard-wired relay logic control systems. 1/14/2019 2

3 PLCs versus Hard-Wired Relay Control PLCs Low cost: Hundreds of contact instructions, timers, and counters can be used in a single program. High flexibility: most changes to the controlled process, can be done in the Hard-wired relay control systems Cost can be very high, and increases as complexity increases. Very limited flexibility: any change in the process will require rewiring. software level. Easier troubleshooting Large space requirement and may take long times to locate faults. Connectivity: The PLC can be connected to the computer networks including Ethernet and wireless networks. Thus the PLC can be controlled and accessed by a Supervisory Control and Data Acquisition system (SCADA). Cannot be connected to a network. 1/14/2019 3

4 PLCs versus Personal Computers PLCs Designed to control industrial processes in real time at a low cost. have enhanced current-handling capability, and can sustain harsh environments such as temperature and humidity Personal Computers (PCs) Designed to be user-friendly for a wide range of end users. Not designed to sustain harsh environments and high currents. PLCs have significantly less amount of Enhanced and expensive volatile and memory and processing capability, permanent memories because their purpose is not to be userfriendly, but to perform control tasks in an industrial setting at a minimum cost. Can handle harsh environments of Strong and expensive microprocessors that temperature and humidity Can have only one program loaded. are designed for speed. Can run multiple programs at a time such as internet surfing, word processing, and spread sheets simultaneously.. 1/14/2019 4

5 PLC Architecture & Components (1) PLC The central Processing Unit contains the microprocessor and the memory Central Processing Unit (CPU) Input/Output Memory Microrpocessor Exercise Questions: 1. What type of processor does your computer have? 2. What is the clock frequency of your computer s processor? 1/14/2019 5

6 PLC Architecture & Components (2) Siemens PLCs have all or some of the following components: Power Supply Central Processing Unit: contains the following - Microprocessor: Siemens S7-300 PLCs use 16-bit and 32-bit processors made by the German-based Infineon Technologies AG. Some families of the PLCs manufactured by Allen-Bradley were based on the Motorola processor. - EEPROM/ RAM memory storage - MicroSD card Slot (after Lithium battery (in models before 2002) - MPI connection: for MPI interface - DP connection: for Profibus interface (Not always provided) - Ethernet connection : for Profinet connection (not in S300) - Status indicators: SF, Run, Stop, - Mode selector: Stop, Run, MRES Input/Output Modules: can be fixed (such as on the S314 stations) or mudular (such as in the S315 station in the lab). Other modules: such as the interface and communication modules 1/14/2019 6

Programmable Logic Controllers Siemens Families of PLCs: Simatic S7-1500

7 Programmable Logic Controllers Siemens Families of PLCs: Simatic S Simatic S Simatic S7-400 Simatic S7-300 Logo Simatic S7-200 Jan 2016

8 Memory The smallest storage unit in memory is the Bit Every eight bits are assembled in one Byte. Every two bytes together make up a Word. The right most bit in a word is the Least Significant Bit (LSB) The left most bit is the Most Significant Bit (MSB). Two words together form the 32-bit long Double Word. 1/14/2019 8

9 Prefixes Decimal Prefixes Binary Prefixes Value Symbol Value Symbol kilo = 10 3 = 1000 Example: 5 km = 5000 meters Mega = 10 6 = 1,000,000 Example: 3 MHz = 3,000,000 hertz k Kilo = 2 10 = 1024 Example: 5 KB = 5120 Bytes M Mega = 2 20 = 1,048,576 Example: 3 MB = 3,145,728 Bytes K M Giga = 10 9 = 1,000,000,000 Example: 4 GHz = 4,000,000,000 hertz G Giga = 2 30 = 1,073,741,824 Example: 4 GB = 4,294,967,296 Bytes G 1/14/2019 9

10 Decimal Vs. Binary Prefixes How many bytes are there in 1 KByte? Solution: 1KB = 2 10 Bytes = 1024 Bytes Decimal Binary 1 kilo = Kilo = 2 10 = mega = 1000,000 1 Mega = 2 20 =1,048,576 How many bits are there in 2 KBytes? Solution: = 16,384 bits 1/14/

11 Types of Memory RAM: Random Access Memory. Fastest but volatile ROM: Read Only Memory PROM: Programmable ROM, this memory is non erasable once porgrammed. EPROM: Erasable PROM, this memory is erasable using a strong UV radiation dose. EEPROM: Electrically Erasable PROM, can be erased while in the circuit. Flash memory: non-volatile high capacity memory Note: Other forms of memory storage include Non-stationary (rotating) disks such as Hard Disk Drive, Floppy Disk, and Compact Disk (CD). These forms are normally not used in PLC systems. 1/14/

12 Memory Usage Load Memory: A flash type of memory, this part of memory contains the user program and the hardware configuration. In Siemens PLCs built after 2002, this memory is implemented in the memory card. Work Memory: A Random Access Memory (RAM) that is used to temporarily store portions of the program code to execute them. After that portion of the program code is executed, it is erased from the work memory System Memory: A Random Access Memory (RAM) that is used to store variables when running and executing the program such as variables of timers, counters, memory bits,..etc. 1/14/

13 Real Time Definition: A system operates in real time when it reacts to an event that occurs on the field within a time constraint. Examples: 1. The airbag system: must respond to a collision in real time so that airbags are deployed in the right time. 2. Real-Time surveillance and tracking in UAVs (Drones): cameras are connected to a network ( online ) for processing to respond to events that take place. 3. Non-real time ( offline ) surveillance of the Sonar underwater drones: sonar scans are recorded to be processed after submarine emerges from water. 1/14/

14 Background Why binary? Easier to have 2 states On or OFF, thence simpler electronics The smallest unit is the bit 1 byte = 8 bits 1 word = 2 bytes 1 Double Word = 4 bytes = 32 bits 1/14/

generation C++, C, Java, Visual basic Ladder Logic, Matlab,

15 Introduction to computer programming Assembler Compiler 1st generation Machine Code 2nd generation Assembly Language 3rd generation C++, C, Java, Visual basic Ladder Logic, Matlab, Basic, Pascal,..etc 4th generation LabView, SPSS, Simulink Punch cards 1/14/

16 Programmable Logic Controllers In this course, you will use the Siemens PLCs. Can you name other manufacturers of PLCs? Siemens Families of PLCs: Simatic S Simatic S Simatic S7-400 Simatic S7-300 Simatic S7-200 Logo 1/14/

17 Review Decimal and Binary numbers Decimal numbers have a base of 10 Binary numbers have a base of 2 Decimal Binary Base 10 0, 1, 2, 3, 4. 8, 9 kilo 10 3 = 1000 Use small k 2 0, = 1024 Use capital K Mega 10 6 = 1000, = 1,048,576 Giga 10 9 = 1000,000, /14/

18 Decimal and Binary Numbers Example 1: Fill in the blank: 1 µm = 10-6 meter 1 Kg = 1000 grams 6 MHz = Hz 6,000, MB = 6,291,456 Bytes 1 Nibble = 4 bits 1 Byte = 8 bits 1 word = 2 bytes = 16 bits 1/14/

19 Example 2: How many bytes are there in 16 KB? 16 KB = 16 * 1024 = 16,384 Bytes How many bytes are there in 1 MB? 1 MB = 2 20 = 1,048,576 How many bits are there in 24 KB? number of bytes = 24 * 1024 = 24,576 but there are 8 bits in a byte thus, number of bits = 24,576 * 8 = 196,608 bits 1/14/

20 What type of memory is volatile and therefore only used of storing variables? Only one answer 1. ROM 2. FLASH 3. RAM 4. EPROM 5. PROM 1/14/

Microprocessors/Microcontrollers

Microprocessors/Microcontrollers A central processing unit (CPU) fabricated on one or more chips, containing the basic arithmetic, logic, and control elements of a computer that are required for processing