Industrial IT. Teaching Material By: Geir Hovland. Lecture 2 part 1 Introduction to systematic PLC programming IEC standard Assignment #1

Transcription

1 Introduction Lecture 2 part 1 Introduction to systematic PLC programming IEC standard Assignment #1 Plant Model Teaching Material By: Geir Hovland Host PC Process or I/O I/O Signals Physical Controller 1

2 Contents International Control programming standard IEC history and benefits IEC software model hierarchy IEC fundamentals and elements IEC programming languages Programmable Logic Controllers Functional description using Flowcharts and State machine Functional description to IEC languages IEC languages conversion methodology Introduction of Assignment number 1 2

3 IEC standard IEC Programming languages / Industrial Control Programming...with support for people with different backgrounds 3

4 IEC standard Users? Which Users? Process cntrl Education Discrete Mnf System Integrator YOU?? Programming Maintenance Installation 4

5 IEC standard Users? Which Users? Offshore drilling / pipe-handling equipment Renewable Energy (Wind-Turbines, Hydro Power,...) Automobile production lines Water treatment plant Food processing and packaging machinery Cable manufacturing Semi-conductor clean room automation Theme-park roller coasters Nuclear waste treatment plant This wide range encompass different skills 5

6 IEC standard What is the Benefit of such a Standard? Reduced waste of human resources (in training, debugging, maintenance and consultancy) Creating a focus to problem solving via software re-usability (reduced application investment and supplier dependency) Reduced misunderstandings and errors Programming techniques usable in more environments (general industrial control) Combining harmonously different components from different locations, companies or countries, or projects Increased connectivity (investment protection) Software Library Function Block "Heating" Function "LIMIT" Function "TEST" Function Block "Turning" Function Block "Feeding" 6

7 IEC standard Key quality features of IEC Structured software - through use of Configuration, Resource and Program Organization Units (POUs) Strong Data Typing - through languages that restrict operations to only apply to appropriate types of data Execution control - through use of tasks Complex sequential behaviour - through Sequential Function Charts Software encapsulation - through use of POUs, structures and complex data types. 7 7

8 IEC standard International Language Standardization NEMA Programmable Controllers Committee formed (USA) GRAFCET (France) DIN 40719, Function Charts (Germany) NEMA ICS-3-304, Programmable Controllers (USA) IEC SC65A/WG6 formed DIN , Programmable Controller (Germany) IEC 65A(Sec)38, Programmable Controllers MIL-STD-1815 Ada (USA) IEC SC65A(Sec)49, PC Languages IEC SC65A(Sec)67 IEC 848, Function Charts IEC 64A(Sec)90 IEC Type 3 report recommendation IEC name change 96 IEC: International Electrotechnical Commission. The current (third) edition was published in February 2013, see 8

9 IEC standard Advantages of IEC Internationally accepted standard Step by step all suppliers will support it Uniform structures, languages, and the way of handling It saves you time Unique software model and data/ type concept You only have to learn it once for different controller types Reduced misunderstandings and errors Standard functions and function blocks Reusability of tested software 9

10 IEC standard Advantages of IEC Supports safety and quality programming Easy and comfortable structuring Data typing prohibits programming errors Provides the best language for each problem Consistent specifications of 5 languages Two textual and two graphical languages One structuring language, providing an overview Availability of high level language Possibility to mix different languages 10

11 Software hierarchy IEC Software Model Configuration A Resource L Resource L Task1 Task2 Task3 Task4 Program P1 Program P2 Program P3 Program P4 FB1 FB2 FB3 FB4 global and direct addressed variables access paths Task association Access path association 11

12 Operating System Software hierarchy OB1 FC FB DB FB FC Other OB s like OB35 & OB100 (IC s block) FC FB OB - Organization Block FC - Function FB - Function Block DB Data Block Memory OB35 is timed interrupt Default period of 100 ms to be integrated with synchronized system s 12

13 Software hierarchy FC, FB and DB FC can be used for functions without memory FB can be used for «objects» consisting of both functions and memory (DB). Data in the DB will be remembered after the FB has finished. You can use the internal memory of the PLC (M0.0, M0.1, M0.2, MD10, MW20, etc), but this space is limited. It is strongly recommended to use Data Blocks (DB). In this way, one single PLC can run many programs created by different people without memory conflicts. 13

14 Software hierarchy : Example of FC 14

15 Elements IEC : The Common Elements Character set Data types Variables (English...) (BOOL, WORD, INTEGER...) (VAR, VAR_input, VAR_output...) POUs,Program Organisation Units (Function, Function Block...) SFC Elements Configuration elements: (Steps, Transitions...) (Tasks) Basis for software re-use 15

16 Elements IEC Standard Data types Bit string types Integer types (SINT, INT, DINT, LINT) Unsigned integer types (USINT, UINT, UDINT, ULINT) Real types (REAL, LREAL) Time types Character types (STRING) (BOOL, BYTE, WORD, DWORD, LWORD) (TIME, DATE, TIME_OF_DAY, DATE_AND_TIME) Vendor and user defined data types are possible Direct derived, sub range, enumeration Array, structure 16

17 IEC Elementary Data Types Elements Name Type Bits Range BOOL SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL TIME DATE TIME_OF_DAY, TOD DATE_AND_TIME, DT STRING BYTE WORD DWORD LWORD boolean short integer integer double integer long integer unsigned short integer unsigned integer unsigned double integer unsigned long integer real numbers long reals duration date time date and time string 8 bits 16 bits 32 bits 64 bits not fixed not fixed not fixed not fixed variable to to to e-9 to 2.1e9-9.2e19 to 9.2e19 0 to to to 4.3e9 0 to 1.8e20 not fixed not fixed not fixed not fixed variable NA NA NA NA 17

18 Elements Example Boolean Operations: A AND C A OR C B B A XOR C A B AND OR XOR B

19 Elements Bits and Bytes: A BYTE X consists of 8 bits. LSB MSB LSB MSB = Least Significant Bit = Most Significant Bit Bit addresses = X.0, X.1, X.2,, X.7 BYTE value = X.0 + 2*X.1 + 4*X.2 + 8*X *X *X *X *X.7 Range: 0 to

20 Elements Example BIT and BYTE Operations: X := 100; X.5 : = X.5 XOR 1; X = = 100 X X = = 68; X.5 : = X.5 XOR 1; X = = 100; XOR with 1 often used to toggle bits from 0 to 1 to 0. 20

21 Elements IEC Programming Languages IL (Instruction List) - This is effectively mnemonic programming ST (Structured Text) - A BASIC like programming language LD (Ladder Diagram) - Relay logic diagram based programming FBD (Function Block Diagram) - A graphical dataflow programming method SFC (Sequential Function Charts) - A graphical method for structuring programs PS: Siemens has in addition the language SCL (Structured Control Language), which we will use in MAS

22 Elements 22

23 LD Ladder Diagram (LD) Standardized, rationalized set of relay ladder programming symbols Resembling electrical drawing standard A B C - -- / ( ) 23

24 LD Ladder Diagram (LD) Ladder Diagram (LD) is a graphic representation of Boolean equations, combining contacts (input arguments) with coils (output results). The LD language enables the description of tests and modifications of Boolean data by placing graphic symbols into the program chart. LD graphic symbols are organized within the chart exactly as an electric contact diagram. LD diagrams are connected on the left side and on the right side to vertical power rails. A and not B equals C - -- / ( ) 24

25 IL Instruction List (IL) Single Accumulator based execution model Based upon the German Anweisungsliste, AWL Only one operation such as storing a value in the accumulator register, is allowed per line LD ANDN ST A B C 25

26 ST Structured Text (ST) High level language, block structured Syntax resembles PASCAL Complex statements and nested instructions possible Support for Iteration loops (REPEAT-UNTIL; WHILE-DO) Conditional execution (IF-THEN-ELSE; CASE) Functions (SQRT(), SIN()) C:= A AND NOT B 26

27 FBD Function Block Diagram (FBD) Graphical language, widely used in Europe Allows program elements which appear as blocks to be "wired" together in a form analogous to a circuit diagram Used in many applications that involve the flow of information or data between control components A B AND C 27

28 FBD IEC Standard Function Blocks Bitable Edge detection Counters Timers (SR, RS, SEMA) (R_TRIG, F_TRIG) (CTU, CTD, CTUD) (TP, TON, TOF, RTC) Vendor and user defined function blocks are possible 28

29 Functions IEC Standard Functions Bit string functions (AND, OR, XOR, NOT, SHL, SHR, ROL, ROR) Numerical functions (ADD, SUB, MUL, DIV, MOD, EXPT, ABS, SQRT, LN, LOG, EXP, SIN, COS, TAN, ASIN, ACOS, ATAN) Type conversions (e.g. USINT_TO_DINT, BOOL_TO_BYTE) Selection functions (SEL, MIN, MAX, LIMIT, MUX) Comparison functions (GT, GE, EQ, LT, LE, NE) String functions (LEN, LEFT, RIGHT, MID, CONCAT, INSERT, DELETE, REPLACE, FIND) Vendor and user defined functions are possible 29

30 Step 7 Statement Lists and Function Block Diagram Conversion of analog input value 30

31 Step 7 Monitoring: Tags table 31

32 SFC Sequential Function Chart (SFC) Graphical language which provides a diagrammatic representation of program sequences --> flowchart Based on the French Grafcet (IEC 848) Main structure and suitable for rapid diagnostics The basic elements are steps with action blocks and transitions Steps consist of a piece of program that is carried out until a condition specified in the transition is met Programming of complex tasks by dividing in smaller parts Each element can be programmed in any of the IEClanguages such as LD or ST or IL or FB mix or match any of the languages Step 1 N FILL Transition 1 Step 2 S Empty Transition 2 Step 3 32

33 SFC Programming language for describing Sequential Controls Structured program draft Description of the process with steps and transitions Clear, easy to understand by the process, production and operations staff Application examples Presses and Packaging technology Production lines Process technology (start up shutdown) OEM equipment machinery technology Rotating Machinery e.g. compressors, pumps Step 1 Transition Step 2 Transition Action 1 Action 2 Action 1 33

34 PLC What is a PLC? inputs sensors PLC outputs actuators motors, valves roots in the wiring logic originally hardware based: Relays increasingly software based more flexible, easier to modify more efficient, lower costs needs a programming device industrial PC = PLC + programming device On standard PLC s programming device removed after programming special requirements: rough environment no moving parts such as harddisks Designed to last for many years in industrial environments 34

35 PLC A PLC program works in a cyclic manner Cyclic calculation of the output pattern according to the input pattern it starts again when it s finished no inputs during the cycle cycle time depends on the application smart living technology: < min; drives: several ms particular programming languages inputs program outputs inputs cycle time 35

36 Functional description Why Flowchart or State-Machine? PLC programs can become difficult for others to read without documentation Flowchart or state-machine is a standard approach to document a logic program flow Documentation required by ISO 9001 PXXXX-DS011 Design Specification PXXXX-DS021 Functional Description PXXXX-DS024 Program Description PXXXX-DS025 Definition of Variables 36

37 Flowchart 37

38 Conversion Ladder Logic for the Transitions 38

39 Conversion Ladder Logic Functions 39

40 Coversion Ladder Logic Functions and Outputs 40

41 State machine State based design approach A State based system can be described with system states, and the transitions between those states. If the system is in state 1 and A happens the system will then go into state 2, otherwise it will remain in State 1. if the system is in state 2, and B happens the system will return to state 1. 41

42 State machine Case Study : traffic lights Inputs: S1, S2 (walk button) Outputs: L1, L2,, L6 (2 sets of red, yellow, green lights) Green NS ST1 Yellow NS ST2 Green EW ST3 Yellow EW - ST4 4 seconds delay from yellow to green 42

43 State machine Inputs: S1, S2 (walk button) Outputs: L1, L2,, L6 (2 sets of red, yellow, green lights) Green NS ST1 Yellow NS ST2 Green EW ST3 Yellow EW - ST4 4 seconds delay from yellow to green 43

44 State machine 1. Obtain the states 2. Draw the state transition diagram 3. Derive state equations and transient equations 4. Convert to ladder logic System State: L1,L2,.., L6 State description: ST1,ST2,ST3,ST4 and First Scan: FS Delay 4 s T2 ST3 S2 Pressed T3 ST2 ST4 Transients: T1,T2,T3,T4,T5 e.g. T1: transient from ST1 to ST2 T1 S1 pressed ST1 FS T5 T4 Delay 4 s 44

45 State machine Inputs: S1, S2 (walk button) Outputs: L1, L2,, L6 Delay 4 s T2 ST2 ST3 S2 Pressed T3 ST4 3. Derive state equations and transient equations T1 S1 pressed ST1 T5 FS T4 Delay 4 s 45

46 State machine Convert to Ladder Logic 46

47 State machine 47

48 State machine 48

49 Standards Conversion Alternative Implementation with SR Block Equivalent T4 S Q ST1 T5 T1 R 49

50 Standards Conversion Statement List: Example Equivalent A( O ST1 O T4 O T5 ) AN T1 = ST1 50

51 Standards Conversion STL to FBD Equivalent ST1 >=1 T4 >=1 T5 & T1 ST1 51

52 Standards Conversion FBD Arithmetic's: Example 1 Height_volt = 28200*( *Height_ref) 52

53 Standards Conversion FBD Arithmetic's: Example 2 Height_out = (Sensor_real/ )/

54 Bibliography John, K.H. and Tiegelkamp, M., "IEC : Programming Industrial Automation Systems: Concepts and Programming Languages, Requirements for Programming Systems, Decision-Making Aids"; Springer Verlag (2010) Tisserant, E. and Bessard, L. and De Sousa, M., An open source IEC integrated development environment"; IEEE (2007) De Sousa, M. and Carvalho, A., Emerging Technologies and Factory Automation, Proceedings. ETFA'03. IEEE Conference"; IEEE (2003) MAS 400 Lecture notes by Geir Hovland (2010) Design of Control Systems MAS217 lecture note s by Yousef Iskandarani (2011) Berger, H., 2006, Automating with SIMATIC, 3rd edition, Publicis Corporate Publishing Olsson, G. og Piani, G., 1992, Computer Systems for Automation and Control, Prentice Hall