L05 Programmable logic controller

Transcription

1 Simulation and Control of Production Plants L05 Programmable logic controller () Fundamentals, Programming, Testing Dipl.-Ing. Andreas Karlberger Steinbachstr. 53 B, Room 426 Tel.: 0241/ Aachen, November 2010 Outline 1 Introduction 2 Architecture and Functionality of a 3 Programming according to IEC Test Strategies for Programs Page 1

2 Schematic structure of an electrical control system and flow of signals input layer control signal modulation signal processing signal modulation (amplification) & signal flow actuator layer switch push button photo-electric relay valve lamp motor display M production system user Page 2 Operation fields of Video: production line assembly line logistics [Source: ABB/Renault] Video: mechanical press machine tool automation in buildings [Source: Chiron] Page 3

3 Programmable Logic () and hard-wired Controls a1 S1 S2 A1 hard-wired control cheaper than for simple applications (less than 5 relays) faster than due to parallel wiring and avoidance of sequential process of the control program In safety-critical applications advantage of lower complexity and simple detection of malfunctions complies with safety regulations (otherwise specialized safety is required, e.g. Pilz Co.) Programmable Logic Controller () more flexible and better performance cheaper than hard-wired control for more complex applications (from 5 relays onwards) Page 4 Programmable Logic (), PC with Slot and Soft- Hardware-: power supply, CPU, and digital/analog In- and Outputs fieldbus or MPI (mulitple point interface) are responsible for communication» programming interface Slot : independent of an operating System hard real-time conditions low failure ratio direct access to the host computer high arithmetician performance Soft : is based on Windows-NT soft real-time conditions higher failure ratio short life span Page 5

4 Area of responsibility control of functional units logical operations interlocking optional sequences... user interface to machine operator (task sharing with NC) input elements (push-buttons, switches,...) actuators (lamps, text displays,...) monitoring and diagnosis time measuring validity check error handling (text or graphics)... data exchange with other controls coupling with NC communication with host computer or other systems... specialized tasks tool management production data acquisition... Page 6 Task sharing between NC and on machine tools I O Control panel O O I I M-instructions NC stop NC program NC Matching control (power sections) Machine desired paths actual paths Numerical Control (NC) geometrical path information work pieces and tool paths to be traversed technological instructions e.g. cutting speed, feed rate, spindle speed switching functions e.g. tool changes, cooling lubricant on/off, part loading and unloading pass as switching instructions to Programmable Logic Controller linking switching instructions with feedback from the machine tool transformation into control instructions for the switching units Page 7

5 Outline Introduction Architecture and Functionality of a Programming according to IEC Test Strategies for Programs Page 8 Architecture of a typical Modular structure Hardware Software Advantages Classic Manufacturerspecific Manufacturerspecific Tried and tested, in widespread use, proven industrial robustness, long product cycles MMI NC Integrated structure in NC CPU of NC Special software for -NC Lower-priced hardware, integrated communication of -NC Plug-in board in NC with own CPU same software as classic Lower-priced hardware, integrated communication of -NC, shorter cycle time than software MMI NC NC, and MMI as software components in IPC IPC -plug-in board in IPC Special software for Similar software to classic PC used for MMI, data processing and control task, no special hardware required PC used for MMI, data processing etc., otherwise like classic IPC as plugin board in Same software as classic PC used mainly for data processing, otherwise like classic Page 9

6 control achitectures Conventional wiring Decentralized I/O Intelligent I/O I/O terminals cabinet Process 1 Process 1 one central all I/O sub-assemblies in central cabinet Y-connected wiring to process signals Bus I/O terminals cabinet Process 1 Process 1 I/O terminals one central process-near I/O sub-assemblies bus connection to Higer-level Small Bus I/O terminals Process 1 Process 1 Small n decentralized process-near s n cabinets advantages disadvantages very small process-near space requirement only one cabinet high wiring effort small process-near space requirement significantly reduced wiring effort several small cabinets simplified implementation complete system shut-down, if a fails slower strict functional separation clear wiring system short cycle time for program if components fail, system remains partly functional faster large process-near space requirement own cabinet (incl. power supply per ) Page 10 Hardware components of a analogue and digital signals analogue and digital signals switches push buttons photo-electric relay Input ports marker control unit memory timer Output ports M Valve lamp motor display Accumulator counter copy of situation address register Interface to programmable device Page 11

7 Project data of a task-system (SIEMENS S7-) engineering system serial memory system data modules code modules data modules target-system main storage code and data mainly important in run-state program code user data system memory Image of the current process counter timer local data stack input signals output signals hardwareconfiguration user program symbolism marker Page 12 How works U PAE0.2 S PAE0.4 Anweisung Cyclic processing of the program in normal cases, the sequence of instructions stored in the program memory runs cyclically the whole program is processed continuously Event-controlled processing (interrupt) program cycle is interrupted by a signal from the process (e.g. emergency stop) for running a special routine (e.g. emergency stop routine) program cycle is then continued (unless main program has been generally interrupted) Time-controlled processing program cycle is interrupted by an internal time signal (alarm clock) for running a special routine program cycle then continues Page 13

8 cyclic operation mode > > put on inputs signals user program copy of the input situation cyclic processing Program length Memory size 1. instruction 2. instruction 3. instruction jump instruction last instruction jump the instructions of the user program are worked out step by step. when an input-signal occures, there is an access to the input situation copy set output signals copy of the output situation is shifted to the outputs Page 14 Functions of a basic functions inputs (logical operations) AND OR _ NOT x other functions arithmetical operations addition + subtraction - comparative operations greater than > smaller than < equal to = jump functions call jump to go to data processing Save load delete outputs assign set reset = S R more complex functions time functions counters controllers positioning axes Page 15

9 Signals: binary, digital, analogue voltage binary signal 30V 15V 5V -3V voltage 12V 1 0 decimal number time t1 binary system converter analogue digital 0 MSB LSB time register is a one bit signal only two possible signal states (0 or 1) Input and output only measure the signal» functionality is dependent on user program digital signal binary line e.g. to set the digits of a display 1 byte := 8 bit 1 W:= 2 byte (16 bit) 1 DW:= 2W (32 bit) analogue signal to measure voltage, temperature or force possible input-values: ±10V, 4-20mA, 0-300Ω resolution: 9 to 15 bit excluding one bit sign Page 16 Example for different versions (SIEMENS) Page 17

10 Outline Introduction Architecture and Functionality of a Programming according to IEC Test Strategies for Programs Page 18 Programming devices Handheld PC based past Notebook time Page 19

11 software development phases AN I 3.0 A I 4.1 O I 2.4 S Q 3.5 control task specification program design programming function specification Control hardware Program structure Re-usability Design of program modules Instruction list Ladder diagram Function plan Programming languages program testing service and support Manual program analyses Debugging Simulation Documentation Upgrades Corrections Page 20 Objectives and benefits of IEC Problem Growing complexity of systems Increased engineering effort Higher cost Goal Standardized programming languages Independence of manufacturer-specific control hardware and programming systems Benefits Manufacturer ( hardware and software) Joint development and use of (basic) functions User Manufacturer-independent programming Standardized programming systems Increased portability, reuse, extension and adaptation of programs Page 21

12 programming language according to IEC Configuration part (optional) program PROGRAM... Declaration part Organization part (Program body) END_PROGRAM TYPE FUNCTION BLOCK VAR AUTO:BOOL; T_VOR:TIME;... END_VAR.. CASE N OF 1:FUNCTION_1 (...); 2:FUNCTION_2 (...);... END_CASE LD AND OR ST Instruction List (IL) Var_1 %IX1 %QX17 Var_2 Structured Text (ST) IF R1 THEN Z:= -1; ELSE Z:= 1; END_IF; Ladder Diagram (LD) Function Block Diagram (FBD) & Sequential Function Chart (SFC) text based graphical Page 22 Switching symbols for Ladder Diagram (LD) Nomenclature Wiring Diagram Ladder Diagram (LD) Function Inputs (Switches) Normally open contacts Normally closed contacts Outputs (Relays) ( ) Relays or signal output elements ( ) Page 23

13 Instruction List (IL) Mnemonic symbols of Instruction List OR Operations AND NOT Mnemonic symbols O A N Comparison between Instruction List and Ladder Diagram Operations Instruction List Ladder Diagram AND AND NOT Assign A I1 AN I2 = Q1 I1 I2 Q1 Bracket Open ( Bracket Close ) Assign = OR OR SET O I1 O I2 S Q1 I1 I2 Q1 S Set Reset S R Page 24 General programming structures cyclic OB1 programming process linear program complete process runs in OB1 CPU works out the instructions in sequence OB1 CALL FB10 FB10 control motor DB10 subdivided program program is divided into several modules cyclic each module represents only one functionality CALL FC20 messages FC20 advantage: - easier to read as a linear program - main-loop and several sub functions OB1 CALL FB20 parameter 1 FB20 control motor DB20 structured program program is divided into several modules CALL FB20 parameter 2 messages FB20 DB21 possible to call the same sub functions frequently different data-modules (DB20, DB21) necessary Page 25

14 Example of complex sequence control Abstract layer Detailed layer T3 S3 Sawing T4 S4 Turning T5 S8 Assemble T9 OR-Branching AND- Branching Internal turning S5 AND- Combination OR- Combination T6 S6 Milling T7 S7 Drilling T8 Transition T7: (e.g. in LD) Step S7: (e.g. in IL) A I2 Starting position? S Q1 Set fast forward S M1 Set stepmarker 1... I7.1 I7.2 I5.0 Condition for transition (e.g. milling is over, a drill is clamped.) A M1 Step 1? A I3 Feed rate engagement? R Q1 Reset fast forward S Q2 Set feed rate R M1 Reset stepmarker 1 S M2 Set stepmarker 2 A M1 Step 2? A I4 Drilling depth reached?... release drilling... Q4.1 (and so on) Page 26 Outline 1 Introduction 2 Architecture and Functionality of a 3 Programming according to IEC Test Strategies for Programs Page 27

15 Simple test procedure for programs set input observe output control desk user correction of errors in software programming unit switches and buttons I1 I2 I3 I4 I5 lights Q1 Q2 Q3 Q4 Q5 input elaboration of the program output generation and modification of the program Page 28 Set-up of a test environment for programs User Simulation computer - Planning and control of the simulation Signal Influencing Machine model Input Read input - Process monitoring Actual process status Output Calculate program - - Influencing the simulation Error recognition by comparing sequences and specification - - Simulation of control process behavior Application-oriented simulation elements Write output cyclic Page 29

16 Mechatronic Model Definition of Modelling Scope and Detail Scope What are the functions of the machine? Which functions are crucial for the simulation objectives? Definition of simulation objectives model of mechatronic behaviour Level of detail What are the physical effects does the systems contain? How can the behaviour be abstracted? Definition of modelling effort and quality Page 30 Structure of a Hardware-in-the-Loop-Simulation Human Machine Interface program management, tool management, machine parameters, etc. HMI HMI MCP MCP Machine control panel feed release, program start, emergency stop MPI, Ethernet visual control, additional simulations NC NC DPR MPI, Profibus mechatronic behaviour simulation E/A E/A I/O-component bypassed model of the mechatronic behaviour PCI-card: Simulation of I/Os at the Profibus Page 31

17 E.g. SINUMERIK MS - graphical user interface drag & drop elementparametrisation component library machine element machine model new machine elements can easily be dragged out of the component library and dropped into the machine model the component type editor enables the creation of new machine elements in highlevel languages Page 32 Example for modelling mechatronic behaviour of machine tools (1/2) Switch door closed Model of a door switch simple circuit logical signals safety critical function Switch door open Interaction Model Controller motor current const x 1 x 2 mult 1 x 1 x 2 >? temperature sensor, e. g. for spindle monitoring physical behaviour: first order lag element (P-T1) analog signal for the course of temperature logica signals for sensors simulation time const Page 33

18 Example for modelling mechatronic behaviour of machine tools (2/2) pneumaticcylinder digital sensor detection area sensor light barrier x [mm] capture of defined positions signal direction threshhold Page 34 Controller-internal simulation mechatronic behaviour IEC61131, C/C++ e.g. FB Behaviour is implemented in plc-conform code (IEC61131, high level language) Definition of the machine reactions within the plc Control of simulation runs control by internal markeres control via bus systems (external components) programmed error behaviour Feedback: within the programming system ( virtual LEDs ) via bus systems (output to external components) Advantages: no additional hardware components neede scalable simulation of components (stepwise integration) can be directly implemented Aisadvantages: limited possibilities for the definition of mechatronic behaviour models by IEC confirm programming language limited possibilities for visualisation limited possibilites for test automation Page 35

19 Simulation of programs without mechatronic behaviour model -programmng environment program execution integrated plc simulation manipulation, evaluation read value write value runs on standard-pc (stand alone or integrated in a programming system) Graphical representation of a hardware testboard outputs signals as software-switches input signals as software-led with graphical and numerical representation no mechatronic behaviour model Advantages: Verification of control logic with the original code direct testing on the development workplace possible Disadvantages (comp. Hardware testboard) : dynamic processes difficult to simulate high abstraction capabilities required no temporal determination Page 36 Software-in-the-Loop-Simulation: NC-Simulation with virtual NC-Controller tool lists NC part programs NC machine archive linkage with VNCK in background Hard- and Software: NCK on Windows VNCK API-VNCK-Server Screenshot of a NC simulation (RealNC) Controller emulation using the same controller algorithms like original hardware controller developed by the vendor of the controller increased precision of NC output signals only simplified emulation Page 37

20 Connection of Robot- and -Simulation Robot-/- Simulation SiLS -Developmentenvironment OPC > Software- HiLS Hardware- Sequences within plants are mostly controlled control of automation components control of material flow coordination of control sequences virtual ramp-up of a robotised manufacturing cells Hardware-in-the-Loop-Simulation (HiLS) Software-in-the-Loop-Simulation (SiLS) Disadvanteges: limited clock of OPC (typical 100 ms) at SiLS: only one plc can be connected Quelle: Siemens Page 38 Use of the equipment simulation machine model Application area Test of equipments Service / System maintenance Contract development Presentation Education / Training Machine Simulator Advantages Test of critical operation conditions Shorter installation time Higher availability of equipments Clear specification and description of functions Quality assurance and certification Deadline assurance at the contract development Machine will not be occupied for the education / training Page 39

21 Outline Introduction Architecture and Functionality of a Programming according to IEC Test Strategies for Programs Page 40