Berger Automating with SIMATIC S7-1500

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2 Berger Automating with SIMATIC S7-1500

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4 Automating with SIMATIC S Configuring, Programming and Testing with STEP 7 Professional by Hans Berger Second, considerably revised and enlarged edition, 2017 Publicis Publishing

5 Bibliographic information from the Deutsche Nationalbibliothek The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at The author, translators, and publisher have taken great care with all texts and illustrations in this book. Nevertheless, errors can never be completely avoided. The author, translators, and publisher accept no liability, for whatever legal reasons, for any damage resulting from the use of the programming examples. Editor: Dr. Gerhard Seitfudem, Print ISBN epdf ISBN Second, considerably revised and enlarged edition, 2017 Editor: Siemens Aktiengesellschaft, Berlin and Munich Publisher: Publicis Publishing, Erlangen 2017 by Publicis Pixelpark Erlangen eine Zweigniederlassung der Publicis Pixelpark GmbH The publication and all parts thereof are protected by copyright. Any use of it outside the strict provisions of the copyright law without the consent of the publisher is forbidden and will incur penalties. This applies particularly to reproduction, translation, microfilming, or other processing, and to storage or processing in electronic systems. It also applies to the use of individual figures and extracts from the text. Printed in Germany

6 Preface Preface The SIMATIC automation system unites all of the subareas of an automation solution under a uniform system architecture to form a homogenous whole from the field level right up to process control. The Totally Integrated Automation (TIA) concept permits uniform handling of all automation components using a single system platform and tools with uniform operator interfaces. These requirements are fulfilled by the SIMATIC automation system, which provides uniformity for configuration, programming, data management, and communication. This book describes the SIMATIC S automation system. S controllers are compact in design and can be modularly expanded. The CPUs feature integrated bus interfaces for communicating with other automation systems via Industrial Ethernet and, depending on the type of module, via PROFIBUS DP as well. The STEP 7 Professional engineering software in the TIA Portal makes it possible to use the complete functionality of the S controllers. STEP 7 Professional is the common tool for hardware configuration, generation of the user program, and for program testing and diagnostics. STEP 7 Professional provides five programming languages for generation of the user program: Ladder logic (LAD) with a graphic representation similar to a circuit diagram, function block diagram (FBD) with a graphic representation based on electronic circuitry systems, a high-level Structured Control Language (SCL) similar to Pascal, statement list (STL) with formulation of the control task as a list of commands, and finally GRAPH as a sequencer with sequential processing of the user program. STEP 7 Professional supports testing of the user program by means of watch tables for monitoring, control and forcing of tag values, by representation of the program with the current tag values during ongoing operation, and by offline simulation of the programmable controller. This book describes the configuration, programming, and testing of a CPU 1500 V2.0 programmable controller using the STEP 7 Professional V14 engineering software and the S7-PLCSIM V14 simulation software. Erlangen, July 2017 Hans Berger 5

7 The contents of the book at a glance The contents of the book at a glance 1 Start Overview of the SIMATIC S automation system. Introduction to the SIMATIC STEP 7 Professional V14 engineering software. The basis of the automation solution: Creating and editing a project. 2 SIMATIC S automation system Overview of the SIMATIC S modules: Design of an automation system, CPUs, signal, technology and communication modules. 3 Device configuration Configuration of a station, parameterization of modules, and networking of stations. 4 Tags, addressing, and data types The properties of inputs, outputs, I/O, bit memories, data, and temporary local data as operand areas, and how they are addressed: absolute, symbolic, and indirect. Description of elementary and structured data types, data types for block parameters, pointers, user and system data types. 5 Program execution How the CPU responds in the STARTUP, RUN, and STOP modes. How the user program is structured with blocks, what the properties of these blocks are, and how they are called. How the user program is executed: startup characteristics, main program, interrupt processing, troubleshooting, and diagnostics. 6 The program editor Working with the PLC tag table, creating and editing code and data blocks, compiling blocks, and evaluating program information. 7 The ladder logic programming language LAD The characteristics of LAD programming; series and parallel connection of contacts, the use of coils, standard boxes, Q boxes, and EN/ENO boxes. 8 The function block diagram programming language FBD The characteristics of FBD programming; boxes for binary logic operations, the use of standard boxes, Q boxes, and EN/ENO boxes. 9 The structured control language SCL The characteristics of SCL programming; operators and expressions, working with binary and digital functions, control of program execution using control statements. 6

8 The contents of the book at a glance 10 The statement list programming language STL The characteristics of STL programming; programming of binary logic operations, application of digital functions, and control of program execution. 11 The sequential control programming language GRAPH What a sequential control is, and what its elements are: sequencers, steps, transitions, and branches. How a sequential control is configured using GRAPH. Description of the control functions 12 Basic functions: Functions for binary signals: binary logic operations, memory functions, edge evaluations, timer/counter functions. 13 Digital functions: Functions for digital tags: Transfer, comparison, arithmetic, math, conversion, shift, logic and string functions. 14 Program control: Jump functions, calling and ending blocks, working with block parameters, optimized block access, ARRAY and CPU data blocks. 15 Online mode, diagnostics and program test Connecting a programming device to the PLC station, switching on online mode, transferring the project data, and protecting the user program. Loading, modifying, deleting, and comparing the user blocks. Working with the hardware diagnostics. Testing the user program. Measured value recording with the trace function. 16 Distributed I/O Overview: The ET 200 distributed IO system. How a PROFINET IO system is configured, and what properties it has. How a PROFIBUS DP master system is configured, and what properties it has. 17 Communication The communication functions used to implement open user communication. The properties of S7 communication and with what communication functions it is programmed. How PtP communication is implemented. 18 Appendix How a project created using STEP 7 V5.x is migrated to the TIA Portal. How the Web server is configured in the CPU, and what features it offers. Technology objects for counting, measuring, motion control, PID control. How data is logged and recipes are transferred. Testing a user program offline using the S7-PLCSIM simulation software. Machine and plant diagnostics with ProDiag. 7

9 Table of contents Table of contents 1Introduction Overview of the S automation system SIMATIC S programmable controller Overview of STEP 7 Professional Various programming languages Execution of the user program Data management in the SIMATIC automation system Introduction to STEP 7 Professional V Installing STEP Automation License Manager Starting STEP 7 Professional Portal view The windows of the Project view Information system Adapting the user interface Editing a SIMATIC project Structured representation of project data Project data and editors for a PLC station Working with projects Working with reference projects Working with libraries Multilingual projects SIMATIC S automation system S station components S CPUs CPU versions Control and display elements SIMATIC Memory Card Bus interfaces Signal modules Digital input modules Digital output modules Digital input/output modules Analog input modules Analog output modules Analog input/output modules Technology modules

10 Table of contents 2.5 Communication modules Further modules System power supply modules Load power supply modules SIPLUS S Device configuration Introduction Configuring a station Adding a PLC station Adding a module Parameterization of modules Parameterization of CPU properties Addressing modules Assigning parameters to signal modules Configuring a configuration control Configuring a network Introduction Networking a station Node addresses in a subnet Communication services and types of connection Configuring a connection Configuring a PROFINET subnet Configuring a PROFIBUS subnet Tags, addressing, and data types Operands and tags Introduction, overview Operand areas: inputs and outputs Operand area bit memory Operand area: data Operand area: temporary local data Addressing of tags and constants Signal path Absolute addressing Symbolic addressing Addressing a tag part Addressing a constant Indirect addressing Addressing of hardware objects General information on data types Overview of data types Implicit data type conversion Overlaying tags (data type views)

11 Table of contents 4.5 Elementary data types Bit-serial data types BOOL, BYTE, WORD, DWORD, and LWORD BCD numbers BCD16 and BCD Data types CHAR and WCHAR Fixed-point data types without sign USINT, UINT, UDINT, ULINT Fixed-point data types with sign SINT, INT, DINT, and LINT Floating-point data types REAL and LREAL Data types for durations Data types for points in time Structured data types Date and time DATE_AND_TIME (DT) Date and time DATE_AND_LTIME (DTL) Strings STRING and WSTRING Data type ARRAY Data type STRUCT Parameter types Overview Parameter types BLOCK_FC and BLOCK_FB (STL) Parameter type DB_ANY Parameter type VOID Parameter types POINTER, ANY, and VARIANT Parameter type ARRAY[*] Pointer Introduction Area pointer DB pointer ANY pointer PLC data types Programming a PLC data type Using a PLC data type Comparing PLC data types Renumbering a PLC data type System data types System data types for timer functions System data types for counter functions Start information Hardware data types Executing the user program Operating states STOP operating state Operating mode STARTUP RUN operating state Retentive behavior of operands Creating a user program Program execution

12 Table of contents Structuring of the user program Block types Block properties Block interface Calling a code block Programming recommendations Startup program Organization blocks for the startup program Resetting retentive data Determining a module address Parameterization of modules Main program Organization blocks for the main program Process image updating Cycle time Response time Stopping and delaying the program Time Read system time Runtime meter Interrupt processing Introduction to interrupt processing Time-of-day interrupts Time-delay interrupts Cyclic interrupts Hardware interrupts Assigning interrupts during runtime Reading additional interrupt information Error handling, diagnostics Causes of errors and error responses Local error handling Global error handling (synchronous error) Enabling and disabling synchronous error processing Asynchronous errors Disable, delay, and enable interrupts and asynchronous errors Diagnostics in the user program Diagnostic error interrupt Read start information Reading runtime information Diagnostic functions in the user program Configuring alarms Introduction Configuring alarms according to the alarm number procedure System blocks for alarms Generating a user diagnostics alarm CPU alarm display

13 Table of contents 6Program editor Introduction PLC tag table Creating and editing a PLC tag table Defining and processing PLC tags Comparing PLC tag tables Exporting and importing a PLC tag table Constants tables Programming a code block Creating a new code block Working area of the program editor for code blocks Specifying code block properties Protecting a block Programming a block interface General procedure when programming the control function Programming a control function with LAD and FBD Programming control functions with SCL Programming control functions with STL Programming of a control function with GRAPH Programming a data block Creating a new data block Working area of program editor for data blocks Defining properties for data blocks Declaring data tags Entering data tags in global data blocks Compiling blocks Starting the compilation Compiling SCL blocks Eliminating errors following compilation Working with source files Program information Cross-reference list Assignment list Call structure Dependency structure Consistency check Memory utilization of the CPU Ladder logic LAD Introduction Programming with LAD in general Program elements of ladder logic Programming binary logic operations with LAD NO and NC contacts Series and parallel connection of contacts

14 Table of contents T branch, open parallel branch Negate result of logic operation in the ladder logic Edge evaluation of a binary tag in the ladder logic Validity check of a floating-point tag in the ladder logic Comparison contacts Programming memory functions with LAD Simple and negating coils Set and reset coils Retentive response due to latching Edge evaluation with pulse output in the ladder logic Multiple setting and resetting (filling the bit array) in the ladder logic Coils with time response Programming Q boxes with LAD Memory boxes in the ladder logic Edge evaluation of current flow Timer functions in the ladder logic Counter functions in the ladder logic Programming EN/ENO boxes with LAD Edge evaluation with an EN/ENO box Transfer functions in the ladder logic Arithmetic functions in the ladder logic Math functions in the ladder logic Conversion functions in the ladder logic Shift functions in the ladder logic Logic functions in the ladder logic Functions for strings in the ladder logic Programming VARIANT functions with LAD Program control with LAD Jump functions in the ladder logic Block end function in the ladder logic Block call functions in the ladder logic Function block diagram FBD Introduction Programming with FBD in general Program elements of the function block diagram Programming binary logic operations with FBD Scanning for signal states "1" and "0" Programming a binary logic operation in the function block diagram AND function in the function block diagram OR function in the function block diagram Exclusive OR function in the function block diagram Combined binary logic operations, negating result of logic operation T branch in the function block diagram Edge evaluation of binary tags in the function block diagram

15 Table of contents Validity checking of floating-point numbers in the function block diagram Comparison functions in the function block diagram Programming standard boxes with FBD Assignment and negating assignment Set and reset boxes Edge evaluation with pulse output in the function block diagram Multiple setting and resetting (filling the bit array) in the function block diagram Standard boxes with time response Programming Q boxes with FBD Memory boxes in the function block diagram Edge evaluation of the result of logic operation in the function block diagram Timer functions in the function block diagram Counter functions in the function block diagram Programming EN/ENO boxes with FBD Edge evaluation with an EN/ENO box Transfer functions in the function block diagram Arithmetic functions in the function block diagram Math functions in the function block diagram Conversion functions in the function block diagram Shift functions in the function block diagram Logic functions in the function block diagram Functions for strings in the function block diagram Programming VARIANT functions with FBD Program control with FBD Jump functions in the function block diagram Block end function in the function block diagram Block call functions in the function block diagram Structured Control Language SCL Introduction Programming with SCL in general SCL statements and operators Programming binary logic operations with SCL Scanning for signal states "1" and "0" AND function in SCL OR function in SCL Exclusive OR function in SCL Combined binary logic operations in SCL Negate result of logic operation in SCL Programming memory functions with SCL Value assignment of a binary tag Setting and resetting in SCL Edge evaluation in SCL

16 Table of contents 9.4 Programming timer and counter functions with SCL IEC timer functions in SCL Counter functions in SCL Programming digital functions with SCL Transfer function, value assignment of a digital tag Comparison functions in SCL Arithmetic functions in SCL Math functions in SCL Conversion functions in SCL Shift functions in SCL Word logic operations, logic expression in SCL Functions for strings in SCL Programming VARIANT functions with SCL Program control with SCL Control statements Block end function for SCL Calling a function (FC) with SCL Call of a function block (FB) with SCL Supply of parameters Statement list STL Introduction Programming with STL in general Structure of an STL statement Entering an STL statement Addressing of 64-bit tags STL networks in LAD and FBD blocks Programming binary logic operations with STL Processing of a binary logic operation, operation step Scanning for signal states "1" and "0" AND function in the statement list OR function in the statement list Exclusive OR function in the statement list Combined binary logic operations in the statement list Control of result of logic operation Programming memory functions with STL Assignment in the statement list Setting and resetting in the statement list Edge evaluation in the statement list Programming timer and counter functions with STL Timer functions in the statement list Counter functions in the statement list Programming digital functions with STL Transfer functions in the statement list Comparison functions in the statement list Arithmetic functions in the statement list

17 Table of contents Math functions in the statement list Conversion functions in the statement list Shift functions in the statement list Word logic operations in the statement list Functions for strings in the statement list Programming VARIANT functions with STL Program control with STL Jump functions in the statement list Block end functions in the statement list Block call function in the statement list Further STL functions Working with status bits Accumulator functions Working with the data block registers Partial addressing of data operands Absolute addressing of temporary local data Working with the address registers Memory-indirect addressing Register-indirect addressing Direct access to complex local tags Null instructions S7-GRAPH sequential control Introduction What is a sequential control? Properties of a sequential control Elements of a sequential control Steps and transitions Jumps in a sequential control Branching of a sequencer Permanent instructions Step and transition functions Processing of conditions Processing of actions Configuring a sequential control General procedure for configuration Programming the GRAPH function block Configuring the sequencer structure Programming steps and transitions Programming permanent instructions Configuring alarms Attributes of the GRAPH function block Calling the GRAPH function block Testing the sequential control Loading the GRAPH function block Settings for program testing

18 Table of contents Using operating modes Synchronization of a sequencer Testing with program status Basic functions Binary logic operations Introduction Working with binary signals AND function, series connection OR function, parallel connection Exclusive OR function, non-equivalence function Negate result of logic operation, NOT contact Memory functions Introduction Simple and negating coil, assignment Single setting and resetting Multiple setting and resetting Dominant setting and resetting, memory boxes Edge evaluation Principle of operation of an edge evaluation Edge evaluation of a binary tag (LAD, FBD) Edge evaluation with pulse output (LAD, FBD) Edge evaluation with a Q box (LAD, FBD) Edge evaluation with an EN/ENO box (LAD, FBD) Edge evaluation with SCL Edge evaluation with STL Timer functions Adding a timer function Pulse generation TP ON delay TON OFF delay TOF Accumulating ON delay TONR Loading a timer function with a duration Resetting a timer function Counter functions Inserting a counter function Up counter CTU Down counter CTD Up/down counter CTUD Digital functions Transfer functions Copy tag, MOVE and S_MOVE box for LAD and FBD Value assignments with SCL Loading and transferring with STL

19 Table of contents Copy tag, MOVE and S_MOVE with STL Reading and writing a VARIANT tag Copy data area with MOVE_BLK_VARIANT Copy data area with MOVE_BLK and UMOVE_BLK Filling a data area with FILL_BLK an UFILL_BLK Transferring a tag from and to a BYTE array Reading and writing with PEEK and POKE (SCL, STL) Changing a byte sequence with SWAP Determining range limits Comparison functions Execution of comparison functions Range comparison with LAD and FBD Testing the floating-point tag, OK contact, OK box Testing a VARIANT pointer with LAD, FBD, and STL Testing a VARIANT pointer with SCL Arithmetic functions Arithmetic functions for numerical values Arithmetic functions for time values Decrementing and incrementing Math functions General function description Trigonometric functions SIN, COS, TAN Arc functions ASIN, ACOS, ATAN Generate square and extract square root Logarithm and power Extract decimal points, generate absolute value and negation Calculating with the CALCULATE box in LAD and FBD Conversion functions Conversion functions CONV, S_CONV and T_CONV Conversion of DB_ANY Conversion functions for floating-point numbers Conversion functions STRG_TO_CHARS and CHARS_TO_STRG Conversion functions STRG_VAL and VAL_STRG Conversion functions ATH and HTA Conversion functions SCALE_X and NORM_X Shift functions General function description Shift to right SHR Shift to left SHL Rotate to right ROR Rotate to left ROL Logic functions Word logic operations Invert, generate one's complement Coding functions DECO and ENCO Selection functions SEL, MUX, and DEMUX

20 Table of contents Minimum selection MIN, maximum selection MAX Limiter LIMIT Editing strings Read symbol name Program control Jump functions Introduction Absolute jump Conditional jump Jump list Jump distributor Loop jump Block end functions Block end function RET (LAD and FBD) RETURN statement (SCL) Block end functions BEC, BEU, and BE (STL) Calling of code blocks Introduction Calling a function FC Calling a function block FB Asynchronously working system blocks EN/ENO mechanism Working with blocks Blocks with optimized and standard access Data types of the local tags Addressing block parameters Supplying the block parameters Transfer of block parameters Data block functions Read data block attributes Reading and writing the load memory ARRAY data blocks System blocks for access to ARRAY data blocks CPU data blocks Online mode, diagnostics and test Connecting a PLC station online Connection of a programming device to the PLC station Resetting the CPU memory Reset to factory settings Transferring project data Loading project data for the first time Reloading the project data Protecting the user program

21 Table of contents Working with online project data Working with the memory card Working with blocks in online mode Introduction Editing an online block Loading and uploading a block Download without reinitialization Working with snapshots Working with setpoints Comparing blocks Hardware diagnostics Status displays on the modules Diagnostics window Diagnostic buffer Online tools Further diagnostic information via the programming device Testing the user program Defining the call environment Testing with program status Monitoring of PLC tags Monitoring and controlling of data tags Testing with watch tables Testing with the force table Measured value recording with the trace function Introduction Creating the trace configuration Recording measured values Distributed I/O Introduction, overview ET 200 distributed IO system ET 200MP ET 200M ET 200SP ET 200S ET 200pro ET 200AL ET 200eco and ET200eco PN PROFINET IO PROFINET IO components Addresses with PROFINET IO Configuring PROFINET IO Coupling modules for PROFINET IO Real-time communication in PROFINET Special PROFINET configurations

22 Table of contents 16.4 PROFwIBUS DP PROFIBUS DP components Addresses with PROFIBUS DP Configuring PROFIBUS DP Coupling modules for PROFIBUS DP Special PROFIBUS configurations System blocks for distributed I/O Reading and writing I/O data Read diagnostic data from a DP standard slave Receive and provide a data record Activate/deactivate distributed station Reconfiguring a PROFINET IO system DPV1 interrupts Isochronous mode Introduction Isochronous mode with PROFINET IO Isochronous mode with PROFIBUS Isochronous mode interrupt Isochronous process image updating Communication Overview Open user communication Basics Data structure of open user communication Establish connection and send data with TSEND_C Establish connection and receive data with TRCV_C Configuring open user communication Further functions for open user communication S7 communication Basics One-way data exchange Two-way data exchange Configuring S7 communication Freeport communication Introduction to Freeport communication Configuring the CM PtP communication module Freeport communication functions Further communication functions USS protocol for drives Modbus RTU Modbus TCP Appendix Migrating a project

23 Table of contents 18.2 Web server Enable Web server Standard Web pages Basic websites Read out service data Initialize Web server and synchronize Web pages (WWW) Technology objects Technology objects for motion control Technology objects for PID control Technology objects for counting and measuring Data logging and transferring recipes Introduction to data logging Using data logging Functions for data logging Introduction to recipe transfer Functions for the recipe transfer Simulation with S7-PLCSIM S7-PLCSIM in general The PLCSIM user interface Testing in S7-PLCSIM with STEP-7 test functions Working with a simulation project Testing with the address area Testing with the SIM table Testing with the sequence table Machine and plant diagnostics with ProDiag Index

24 1 Introduction 1 Introduction 1.1 Overview of the S automation system SIMATIC S is the modular automation system for the medium and upper performance ranges. Different versions of the controllers allow the performance to be matched to the respective application. Depending on the requirements, the programmable controller can be expanded by input/output modules for digital and analog signals and technology and communication modules. The SIMATIC S automation system is seamlessly integrated in the SIMATIC system architecture (Fig. 1.1). SIMATIC S automation system SIMATIC S SIMATIC controllers control the machine or plant. Several versions of the controllers expand the range of use. SIMATIC HMI Operator control and monitoring for controlling the plant during operation ESC OK SIMATIC NET Networking allows data exchange between devices and online access at any location. SIMATIC ET200 STEP 7 Professional (TIA Portal) The distributed I/O expands the interface to the machine or plant. STEP 7 is the engineering software uring and programming. Fig. 1.1 Components of the SIMATIC S automation system 23

25 1 Introduction The SIMATIC ET200 distributed I/O allows for additional expansion using input/output modules which are connected to the central controller via PROFIBUS DP or PROFINET IO. The distributed stations can be installed in a control cabinet or if provided with special designs for increased mechanical requirements directly on the machine or system. SIMATIC HMI (HMI = Human Machine Interface) is used to control and monitor a machine or plant and its function. Depending on their version, the devices can provide control functions via process images, display system status and alarm messages, and manage the automation data in the form of recipes or measured value archives. SIMATIC NET handles the exchange of data via various bus systems between the SIMATIC controllers, the distributed I/O, the HMI devices, and the programming device. The programming device can be a personal computer, an industrial PC, or a notebook with a Microsoft Windows operating system. The SIMATIC components are configured, parameterized, and programmed using the STEP 7 Engineering Software. The TIA Portal (TIA = Totally Integrated Automation) is the central tool for managing automation data and the associated editors in the form of a hierarchically structured project SIMATIC S programmable controller The most important components of an S programmable controller are shown in Fig Components of an S controller Rack Central controller Power supply module (PS) CPU (central processing unit) Can be plugged onto the rack: Signal modules (SM) Technology modules (TM) Communication modules (CM) ESC OK The rack has 32 slots. An optional power supply occupies slot 0 and the CPU occupies slot 1. To the right of the CPU, there is room for up to 30 modules (including power supply modules). Fig. 1.2 Components of an S controller with standard controller 24

26 1.1 Overview of the S automation system The CPU (central processing unit) contains the operating system and the user program. The user program is saved powerfail-proof on the SIMATIC Memory Card, which is inserted in the CPU. The user program is executed in the CPU's work memory. The bus interfaces present on the CPU establish the connection to other programmable controllers. Signal modules (SM) are responsible for the connection to the controlled machine or plant. These input and output modules are available for digital and analog signals with different voltages and currents. Technology modules (TM) are signal-preprocessing, "intelligent" I/O modules which prepare and process signals coming from the process independent of the CPU and either return them directly to the process or make them available at the CPU's internal interface. Technology modules are responsible for handling functions which the CPU cannot usually execute quickly enough such as counting pulses. Communication modules (CM) allow data traffic in excess of the functionality provided by the standard interfaces on the CPU with regard to protocols and communication functions. The (system) power supply modules provide the internal voltages required by the programmable controller. Up to three system power supply modules can be used in the programmable controller as needed. Load voltages or load currents are provided via external load current supplies (power modules, PM), which can also provide 24 V primary voltage for system power supply modules Overview of STEP 7 Professional STEP 7 is the central automation tool for SIMATIC. STEP 7 requires authorization (licensing) and is executed on the current Microsoft Windows operating systems. Configuration of an S controller is carried out in two views: the Portal view and the Project view. The Portal view is task-oriented. In the Start portal you can open an existing project, create a new project, or migrate a project. A "project" is a data structure containing all the programs and data required for your automation task. The most important STEP 7 tools and functions can be accessed from here via further portals: The Devices & networks portal for hardware configuration, the PLC programming portal for processing the user program, the Motion & technology portal for generating technology objects, the Visualization portal for configuring HMI systems, and the Online & Diagnostics portal for the online mode of the programming device (Fig. 1.3). The Project view is an object-oriented view with several windows whose contents change depending on the current activity (Fig. 1.4). In the Device configuration, the focal point is the working area with the device to be configured. The Device view includes the rack and the modules which have already been positioned. A further window the inspector window displays the properties of the selected module, 25

27 1 Introduction Fig. 1.3 Tools in the Start portal of STEP 7 Professional V14 Fig. 1.4 Example of a Project view: Working area of the device configuration 26

28 1.1 Overview of the S automation system and the task card provides support by means of the hardware catalog with the available modules. The Network view allows networking between PLC and HMI stations. When carrying out PLC programming, you edit the selected block in the working area. You are again shown the properties of the selected object in the inspector window, where you can adjust them. In this case, the task card contains the program elements catalog with the available program elements and statements. The same applies to the processing of PLC tags or to online program testing using watch tables. And you always have a view of the project tree. This contains all objects of the STEP 7 project. You can therefore select an object at any time, for example a program block or watch table, and edit this object using the corresponding editors which start automatically when the object is opened. In addition there is a library view, in which the elements of the project library and the opened global libraries can be edited Various programming languages You can select between five programming languages for the user program: ladder logic (LAD), function block diagram (FBD), structured control language (SCL), statement list (STL), and sequential control (GRAPH) (Fig. 1.5). Using the ladder logic, you program the control task based on the circuit diagram. Operations on binary signal states are represented by serial or parallel arrangement of contacts and coils. Complex functions such as arithmetic functions are represented by boxes which you arrange like contacts or coils in the ladder logic. Using the function block diagram, you program the control task based on electronic circuitry systems. Binary operations are implemented by linking AND and OR functions and are terminated by memory boxes. Complex boxes are used to handle the operations on digital tags, for example with arithmetic functions. Structured control language is particularly suitable for programming complex algorithms or for tasks in the area of data management. The program is made up of SCL statements which, for example, can be value assignments, comparisons, or control statements. Using the statement list, you program the control task using a sequence of statements. Every STL statement contains the specification of what has to be done, and possibly an operand with which the operation is executed. STL is equally suitable for binary and digital operations and for programming complex open-loop control tasks. Using GRAPH, you program a control task as a sequential control in which a sequence of actions prevails. The individual steps and branches are enabled by step enabling conditions which can be programmed using LAD or FBD (Fig. 1.6). 27

29 1 Introduction Ladder logic LAD Function block diagram FBD Structured Control Language SCL Statement list STL Fig. 1.5 Example of representation in LAD, FBD, SCL, and STL 28

30 1.1 Overview of the S automation system Fig. 1.6 Example of a GRAPH sequencer and step configuration Execution of the user program After the power supply has been switched on, the control processor checks the existing hardware and parameterizes the modules. A startup program is then executed once, if present. The startup program belongs to the user program which you produce. Modules can be initialized, for example, by the startup program. The user program is usually divided into individual sections called "blocks". Organization blocks (OB) represent the interface between operating system and user Execution of the user program Operating system User program Switching on OB FB FC FB FC Startup program Operating state STARTUP Updating of inputs and outputs OB FB FC FB FC Main program Operating state RUN Alarm and error program Interruption (alarm or error) Interruption OB FB FC FB FC Fig. 1.7 Execution of the user program 29