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Automating withSTEP7inSTLandSCLProgrammable ControllersSIMATIC S7-300/400

by Hans Berger

3rd revised edition, 2005

Publicis Corporate Publishing

Tableof Contents

Table of Contents

Introduction 21

1 SIMATIC S7-300/400Programmable C o n t r o l l e r . . . . 22

1.1 Structure oftheProgrammable Controller 22

1.1.1 Components 221.1.2 S7-300 Station 221.1.3 S7-400 Station 241.1.4 Fault-Tolerant SIMATIC 251.1.5 Safety-Relevant SIMATIC . . . . 261.1.6 CPU Memory Areas 27

1.2 Distributed I/O 31

1.2.1 DP Master System 311.2.2 DP Master 321.2.3 DPSlaves 321.2.4 Further Network Components. . . 331.2.5 Connection to PROFIBUS PA . . 341.2.6 Connection to AS-Interface . . . . 341.2.7 Connection to a Serial Interface. . 35

1.3 Communications 36

1.3.1 Introduction 361.3.2 Subnets 371.3.3 Communications Services 391.3.4 Connections 40

1.4 Module Addresses 41

1.4.1 Signal Path 411.4.2 SlotAddress 421.4.3 Module Start Address 421.4.4 Diagnostics Address 431.4.5 Addresses for Bus Nodes 43

1.5 Address Areas 43

1.5.1 User Data Area 431.5.2 Process Image 441.5.3 Consistent User Data 451.5.4 BitMemories 46

2 STEP 7 Programming Software . 47

2.1 STEP 7 Basic Package 47

2.1.1 Installation 472.1.2 Automation License Manager . . . 472.1.3 SIMATIC Manager 482.1.4 Projects and Libraries 492.1.5 Multiprojects 512.1.6 Online Help 52

2.2 Editing Projects 52

2.2.1 Creating Projects 522.2.2 Managing, Rearranging and

Archiving 542.2.3 Project Versions 542.2.4 Creating and Editing Multiprojects. 55

2.3 Configuring Stations 56

2.3.1 Arranging Modules 582.3.2 Addressing Modules 582.3.3 Parameterizing Modules 582.3.4 Networking Modules with MPI . . 592.3.5 Monitoring and Modifying

Modules 59

2.4 Configuring the Network 59

2.4.1 Configuring the Network View. . . 602.4.2 Configuring a DP Master System

with the Network Configuration . . 612.4.3 Configuring Connections 622.4.4 Network Transitions 652.4.5 Loading the Connection Data . . . 662.4.6 Adjusting Projects in the

Multiproject 66

2.5 Creating the S7 Program 68

2.5.1 Introduction 682.5.2 Symbol Table 682.5.3 STL Program Editor 702.5.4 SCL Program Editor 742.5.5 Rewiring 772.5.6 Address Priority 782.5.7 Reference Data 79

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2.5.8 Multilingual Comments and

Display Texts 80

2.6 Online Mode 81

2.6.1 Connecting a PLC 812.6.2 Protecting the User Program. . . . 822.6.3 CPU Information 832.6.4 Loading the User Program into

the CPU 832.6.5 Block Handling 842.7 Testing the Program 87

2.7.1 Diagnosing the Hardware 872.7.2 Determining the Causeofa STOP. 872.7.3 Monitoring and Modifying

Variables 872.7.4 Forcing Variables 892.7.5 Enabling Peripheral O u t p u t s . . . . 902.7.6 STL Program Status 912.7.7 Monitoring and Controlling Data

Addresses 932.7.8 Debugging SCL Programs 93

3 SIMATIC S7 Program 96

3.1 Program Processing 96

3.1.1 Program Processing Methods . . . 963.1.2 Priority Classes 973.1.3 Specifications for Program

Processing 98

3.2 Blocks 100

3.2.1 Block Types 1003.2.2 Block Structure 1013.2.3 Block Properties 1033.2.4 Block Interface 105

3.3 Addressing Variables 107

3.3.1 Absolute Addressing of Variables 1073.3.2 Indirect Addressing 1083.3.3 Symbolic Addressing of Variables 108

3.4 Programming Code Blockswith STL 110

3.4.1 Structure of an STL Statement. . 1103.4.2 Programming STL Code Blocks

Incrementally 1103.4.3 Overview Window 1113.4.4 Programming Networks 1123.4.5 Source-File-Oriented Program-

ming of STL Code Blocks . . . . 113

3.5 Programming Code Blockswith SCL 117

3.5.1 Structure of an SCL Statement . . 1173.5.2 Programming SCL Code Blocks . 117

3.6 Programming Data Blocks . . . . 121

3.6.1 Programming Data BlocksIncrementally 121

3.6.2 Source-Oriented Data BlockProgramming 124

3.7 Variables and Constants 126

3.7.1 General Remarks ConcerningVariables 126

3.7.2 General Remarks RegardingData Types 126

3.7.3 Elementary Data Types 1273.7.4 Complex Data Types 1273.7.5 Parameter Types 130

Basic Functions 131

4 Binary Logic Operation« . . . . 132

4.1 Processing a Binary LogicOperation 132

4.2 Elementary Binary LogicOperations 134

4.2.1 ANDFunction 1354.2.2 ORFunction 1354.2.3 Exclusive OR Function 135

4.3 Negating the Result of theLogic Operation 137

4.4 Compound Binary LogicOperations 137

4.4.1 Processing Nesting Expressions . 1384.4.2 Combining AND Functions

AccordingtoOR 1404.4.3 Combining OR and Exclusive OR

Functions According to AND. . . 1404.4.4 Combining AND Functions

According to Exclusive OR. . . . 1404.4.5 Combining OR Functions and

Exclusive OR Functions 1414.4.6 Negating Nesting Expressions . . 141

5 Memory Functions 142

5.1 Assign 142

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5.2 SetandReset 142

5.3 RS Flipflop Function 144

5.3.1 Memory Functions with ResetPriority 144

5.3.2 Memory Function with SetPriority 144

5.3.3 Memory Function in a BinaryLogic Operation 144

5.4 Edge Evaluation 145

5.4.1 Positive Edge 1465.4.2 Negative Edge 1465.4.3 Testing a Pulse Memory Bit. . . 1475.4.4 Edge Evaluation in a Binary

Logic Operation 1475.4.5 Binary Sealer 148

5.5 Example of a Conveyor BeltControl System . 148

6 Move Functions 152

6.1 General Remarks on Loading

and Transferring Data 152

6.2 Load Functions 154

6.2.1 General Representation of aLoad Function 154

6.2.2 Loading the Contents ofMemory Locations 154

6.2.3 Loading Constants 1556.3 Transfer Functions 156

6.3.1 General Representation of aTransfer Function 156

6.3.2 Transferring to Various MemoryAreas 156

6.4 Accumulator Functions 157

6.4.1 Direct Transfers Between

Accumulators 157

6.5 Exchange Bytes in Accumulator 1. 158

6.6 System Functions for DataTransfer 159

6.6.1 Copying Memory Area 1606.6.2 Uninterrüptible Copying of

Variables 1606.6.3 Initializing a memory area. . . . 1616.6.4 Copying STRING Variables . . 1616.6.5 Reading from Load Memory . . 161

6.6.6 Writing into the Load Memory. . 162

7 Timer Functions 164

7.1 Programming a Timer 164

7.1.1 Starting a Timer 1647.1.2 Specifying the Time 1657.1.3 Resetting a Timer 1667.1.4 Enabling a Timer 1667.1.5 Checking a Timer 1667.1.6 Sequence of Timer Instructions . 1677.1.7 Clock Generator Example . . . . 167

7.2 Pulse Timers 168

7.3 Extended Pulse Timers 170

7.4 On-Delay Timers 172

7.5 Retentive On-Delay Timers . . . 174

7.6 Off-Delay Timers 176

7.7 IEC Timer Functions 178

7.7.1 Pulse Generation SFB 3 TP . . . 1787.7.2 On Delay SFB 4 TON 1797.7.3 Off Delay SFB 5 TOF 179

8 Counter Functions 180

8.1 Setting and Resetting Counters. . 180

8.2 Counting 181

8.3 Checking a Counter 182

8.4 Enabling a Counter 182

8.5 Sequence of Counter Instructions 183

8.6 IEC Counter Functions 184

8.6.1 Up Counter SFB 0 CTU 1848.6.2 Down Counter SFB 1CTD. . . . 1848.6.3 Up-Down Counter SFB 2 CTUD. 185

8.7 Parts Counter Example 185

Digital Functions 189J

9 Comparison Functions . . . . . 190

9.1 General Representation of aComparison Function 190

9.2 Description of the ComparisonFunctions 191

9.3 Comparison Function in a LogicOperation 192

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10 Arithmetic Functions 194

10.1 General Representation of anArithmetic Function 194

10.2 Calculating with Data TypeINT 195

10.3 Calculating with Data TypeDINT 196

10.4 Calculating with Data TypeREAL 197

10.5 Successive ArithmeticFunctions 198

10.6 Adding Constants toAccumulator 1 199

10.7 Decrementing andIncrementing 199

11 Math Functions 201

11.1 Processing a Math Function . . . 201

11.2 Trigonometrie Functions 202

11.3 Are Functions 202

11.4 Other Math Functions 202

12 Conversion Functions 204

12.1 Processing a ConversionFunction 204

12.2 Converting INT and DINTNumbers 205

12.3 Converting BCD Numbers. . . . 205

12.4 Converting REAL Numbers . . . 206

12.5 Other Conversion Functions . . . 207

13 Shift Functions 209

13.1 Processing a Shift Function . . . 209

13.2 Shifting 210

13.3 Rotating 212

14 Word Logic 214

14.1 Processing a Word LogicOperation 214

14.2 Description of the Word LogicOperations 216

Program Flow Control 217]

15 Status Bits 218

15.1 Description ofthe Status Bits. . . 218

15.2 Setting the Status Bits and theBinary Flags 220

15.3 Evaluating the Status Bit 222

15.4 Using the Binary Result 224

16 Jump Functions 226

16.1 Programming a Jump Function . . 226

16.2 Unconditional Jump 227

16.3 Jump Functions with RLO andBR 227

16.4 Jump Functions withCCOandCCl 228

16.5 Jump Functions with

OVandOS 230

16.6 Jump Distributor 230

16.7 Loop Jump 231

17 Master Control Relay 232

17.1 MCR Dependency 232

17.2 MCR Area 233

17.3 MCR Zone 233

17.4 Setting and Resetting I/O Bits . . 234

18 Block Functions 236

18.1 Block Functions for Code Blocks. 236

18.1.1 Block Calls: General 23718.1.2 CALL Call Statement 23718.1.3 UC and CC Call Statements . . . 23818.1.4 Block End Functions 23918.1.5 Temporary Local Data 23918.1.6 Static Local Data 242

18.2 Block Functions for Data Blocks . 244

18.2.1 Two Data Block Registers . . . . 24418.2.2 Accessing Data Addresses . . . . 24518.2.3 Open Data Block 24718.2.4 Exchanging the Data Block

Registers 24818.2.5 Data Block Length and Number . 24818.2.6 Special Points in Data Addressing 248

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18.3 System Functions for DataBlocks 250

18.3.1 Creating a Data Block in theWork Memory 250

18.3.2 Creating a Data Block in theLoad Memory 251

18.3.3 Deleting a Data Block 25218.3.4 Testing a Data Block 252

18.4 Null Operations 252

18.4.1 NOP Statements . . . . . . . . . 25218.4.2 Program Display Statements . . 253

19 Block Parameters 254

19.1 Block Parameters in General . . 254

19.1.1 Defming the BlockParameters 254

19.1.2 Processing the BlockParameters 254

19.1.3 Declaration of the BlockParameters 255

19.1.4 Declaration of the FunctionValue 256

19.1.5 Initializing Block Parameters . . 257

19.2 Formalparameters 257

19.3 Actual Parameters 260

19.4 "Passing On" Block Parameters. 263

19.5 Examples 264

19.5.1 Conveyor Belt Example 26419.5.2 Parts Counter Example 26519.5.3 Feed Example 265

Program Processing . 269[

20 Main Program . . . . . . . . . 270

20.1 Program Organization 270

20.1.1 Program Structure 27020.1.2 Program Organization 271

20.2 Scan Cycle Control 272

20.2.1 Process Image Updating 27220.2.2 Scan Cycle Monitoring Time . . 27420.2.3 Minimum Scan Cycle Time,

Background Scanning 27520.2.4 ResponseTime 27620.2.5 Start Information 276

20.3 Program Functions 277

20.3.1 Time 27820.3.2 Read System Clock 28020.3.3 Run-Time Meter 28020.3.4 Compressing CPU Memory . . . 28220.3.5 Waiting and Stopping 28220.3.6 Multiprocessing Mode 282

20.4 Communication viaDistributed I/O 283

20.4.1 Addressing Distributed I/O. . . . 28420.4.2 Configuring Distributed I/O . . . 28820.4.3 Special Functions for

Distributed I/O 29420.4.4 System Functions for

Distributed I/O . . . 298

20.5 Global Data Communication . . . 303

20.5.1 Fundamentals 30320.5.2 Configuring GD communication . 30520.5.3 System Functions for GD

Communication 307

20.6 S7 Basic Communication 307

20.6.1 Station-Internal S7 BasicCommunication 307

20.6.2 System Functions for DataInterchange within a Station . . . 309

20.6.3 Station-External S7 BasicCommunication 310

20.6.4 System Functions for Station-Ex-ternal S7 Basic Communication . 311

20.7 S7 Communication 313

20.7.1 Fundamentals 31320.7.2 Two-Way Data Exchange . . . . 31520.7.3 One-Way Data Exchange 31720.7.4 Transferring Print Data 31820.7.5 Control Functions 31820.7.6 Monitoring Functions 319

20.8 PtP Communication with S7-300C 322

20.8.1 Fundamentals 32220.8.2 ASCII Driver and 3964(R)

Procedure 32420.8.3 RK512 Computer Link 325

20.9 Configuration in RUN 328

20.9.1 Preparation of Modifications toConfiguration 328

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Table of Contents

20.9.2 Changing the Configuration . . . 330

20.9.3 Loading the Configuration. . . . 330

20.9.4 CiR Synchronization Time. . . . 331

20.9.5 Effects on Program Execution . . 331

20.9.6 Controlling the CiR Procedure. . 332

21 Interrupt Handling 333

21.1 General Remarks 333

21.2 Time-of-Day Interrupts 334

21.2.1 Handling Time-of-Day Interrupts 33521.2.2 Configuring Time-of-Day

Interrupts with STEP 7 33621.2.3 System Functions for Time-of-

Day Interrupts 336

21.3 Time-Delay Interrupts 337

21.3.1 Handling Time-Delay Interrupts. 33821.3.2 Configuring Time-Delay

Interrupts with STEP 7 33921.3.3 System Functions for Time-

Delay Interrupts 339

21.4 Watchdog Interrupts 340

21.4.1 Handling Watchdog Interrupts. . 34021.4.2 Configuring Watchdog Interrupts

with STEP 7 341

21.5 Hardware Interrupts 342

21.5.1 Generating a Hardware Interrupt 34221.5.2 Servicing Hardware Interrupts. . 34321.5.3 Configuring Hardware Interrupts

with STEP 7 344

21.6 DPV1 Interrupts 344

21.7 Multiprocessor Interrupt 346

21.8 Synchronous Cycle Interrupts . . 347

21.8.1 Processing Synchronous CycleInterrupts 347

21.8.2 Isochrone Updating of ProcessImage 348

21.8.3 Programming of SynchronousCycle Interrupts with STEP 7 . . 349

21.9 Handling Interrupts 349

21.9.1 Disabling and Enabling Interrupts 34921.9.2 Delaying and Enabling Delayed

Interrupts 350

21.9.3 Reading Additional InterruptInformation 350

22 Restart Characteristics 353

22.1 General Remarks 353

22.1.1 Operating Modes 35322.1.2 HOLD Mode 35422.1.3 Disabling the Output Modules . . 35422.1.4 Restart Organization Blocks . . . 354

22.2 Power-Up 355

22.2.1 STOP Mode 35522.2.2 Memory Reset 35622.2.3 Retentivity 35622.2.4 Restart Parameterization 356

22.3 Types of Restart 357

22.3.1 START-UPMode 35722.3.2 Cold Restart 35722.3.3 Warm Restart . . 35922.3.4 Hot Restart 359

22.4 Ascertaining a Module Address. . 360

22.5 Parameterizing Modules 362

22.5.1 General Remarks onParameterizing Modules 362

22.5.2 System Functions for ModuleParameterization 363

22.5.3 Blocks for Data Record Transfer . 364

23 Error Handling 367

23.1 Synchronous Errors 367

23.2 Synchronous Error Handling . . . 369

23.2.1 Error Filters 369

23.2.2 Masking Synchronous Errors . . . 37023.2.3 Unmasking Synchronous Errors . 37023.2.4 Reading the Error Register . . . . 37023.2.5 Entering a Substitute Value. . . . 371

23.3 Asynchronous Errors 371

23.4 System Diagnostics 374

23.4.1 Diagnostic Events andDiagnostic Buffer 374

23.4.2 Writing User Entries in theDiagnostic Buffer 374

23.4.3 Evaluating Diagnostic Interrupts . 37523.4.4 Reading the System Status List. . 375

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Table of Contents

Variable Handling 378

24 Data Types 379

24.1 Elementary Data Types 379

24.1.1 Declaration of ElementaryData Types 379

24.1.2 BOOL, BYTE, WORD,DWORD, CHAR 380

24.1.3 Number Representations . . . . 38124.1.4 Time Representations 383

24.2 Complex Data Types 384

24.2.1 D A T E A N D T I M E 38424.2.2 STRING 38524.2.3 ARRAY 38624.2.4 STRUCT 388

24.3 User-Defined Data Types . . . . 390

24.3.1 Programming UDTsIncrementally 390

24.3.2 Source-File-OrientedProgramming of UDTs 390

25 Indirect Addressing 392

25.1 Pointers 392

25.1.1 Area Pointer 39225.1.2 DBPointer 39225.1.3 ANY Pointer 394

25.2 Types of Indirect Addressingin STL 395

25.2.1 General . . 39525.2.2 Indirect Addresses 39525.2.3 Memory-Indirect Addressing . . 39625.2.4 Register-Indirect Area-Internal

Addressing 39625.2.5 Register-Indirect Area-Crossing

Addressing 39825.2.6 Summary 398

25.3 Working with Address Registers 399

25.3.1 Loading into an Address Register 39925.3.2 Transferring from an Address

Register 39925.3.3 Swap Address Registers 39925.3.4 Adding to the Address Register . 399

25.4 Special Features of IndirectAddressing 401

25.4.1 Using Address Register AR1. . . 40125.4.2 Using Address Register AR2. . . 40325.4.3 Restrictions with Static Local

Data 403

26 Direct Variable Access 405

26.1 Loading the Variable Address . . 405

26.2 Data Storage of Variables . . . . 406

26.2.1 Storage in Global Data Blocks . . 40626.2.2 Storage in Instance Data Blocks . 40726.2.3 Storage in the Temporary Local

Data 407

26.3 Data Storage when TransferringParameters 410

26.3.1 Parameter Storage in Functions . 41026.3.2 Storing Parameters in Function

Blocks 41226.3.3 "Variable" ANY Pointer . . . . . 412

26.4 Brief Description of the MessageFrame Example 414

Structured Control Language (SCL) . .42lj

27 Introduction, LanguageElements 422

27.1 Integration in SIMATIC 422

27.1.1 Installation 42227.1.2 Setting Up a Project 42227.1.3 Editing the SCL Source 42227.1.4 Completing the Symbol Table . . 42327.1.5 Compiling the SCL Program . . . 42427.1.6 Loading SCL Blocks 42427.1.7 Testing SCL Blocks 42427.1.8 Addresses and Data Types . . . . 42427.1.9 Data Type Views 426

27.2 Addressing 426

27.2.1 Absolute Addressing 42627.2.2 Symbolic Addressing 42627.2.3 Indirect Addressing in SCL . . . 427

27.3 Operators 429

27.4 Expressions 429

27.4.1 Arithmetic Expressions 42927.4.2 Comparison Expressions 43127.4.3 Logical Expressions 431

27.5 Value Assignments 432

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Table of Contents

27.5.1 Assignment for ElementaryData Types 432

27.5.2 Assignment of DT and STRINGVariables 432

27.5.3 Assignment of Strucrures . . . . 43227.5.4 Assigning Fields 432

28 Control Statements 433

28.1 IF Statement 433

28.2 CASE Statement 434

28.3 FOR Statement 434

28.4 WHILE Statement 435

28.5 REPEAT Statement 435

28.6 CONTINUE Statement 436

28.7 EXIT Statement 436

28.8 RETURN Statement 436

28.9 GOTO Statement 436

29 SCL Blocks 438

29.1 SCL Blocks - General 438

29.2 Programming SCL Blocks. . . . 438

29.2.1 Function FC without a FunctionValue 439

29.2.2 Function FC with FunctionValue 439

29.2.3 Function Block FB 43929.2.4 Temporary Local Data 44029.2.5 Static Local Data 44129.2.6 Block Parameters 44129.2.7 Formalparameters 442

29.3 Calling SCL Blocks 442

29.3.1 Function FC without FunctionValue 443

29.3.2 Function FC with FunctionValue 443

29.3.3 Function Block with its OwnData Block 443

29.3.4 Function Block as Local Instance 44429.3.5 Actual Parameters 444

29.4 EN/ENO Mechanism 445

29.4.1 OK Variable 44529.4.2 ENO Output 44529.4.3 EN Input 446

30 SCL Functions 447

30.1 Timer Functions 447

30.2 Counter Functions 448

30.3 Math Functions 449

30.4 Shifting and Rotating 449

30.5 Conversion Functions 450

30.5.1 Implicit Conversion Functions . . 45030.5.2 Explicit Conversion Functions . . 450

30.6 Programming Your OwnFunctions with SCL 452

30.7 Programming Your OwnFunctions with STL 454

30.8 Brief Description of the SCLExamples 454

30.8.1 Conveyor Example 45430.8.2 Message Frame Example 45530.8.3 General Examples 456

31 IEC Functions 457

31.1 Conversion Functions 457

31.2 Comparison Functions 459

31.3 STRING Functions 460

31.4 Date/Time-of-Day Functions . . . 462

31.5 Numerical Functions 463

Appendix 465

32 S5/S7 Converter 466

32.1 General 466

32.2 Preparation 467

32.2.1 Checking Executability on theTarget System (PLC) 467

32.2.2 Checking Program ExecutionCharacteristics 467

32.2.3 Checking the Modules 46932.2.4 Checking the Addresses 469

32.3 Converting 470

32.3.1 Creating Macros 47032.3.2 Preparing the Conversion 47132.3.3 Starting the Converter 47132.3.4 Convertible Functions 472

32.4 Post-Editing 473

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Table of Contents

32.4.1 Creating the STEP 7 Project. . . 47332.4.2 Unconvertible Functions . . . . 47432.4.3 Address Changes 47432.4.4 Indirect Addressing 47532.4.5 Access to "Excessively Long"

Data Blocks 47732.4.6 Working with Absolute Addresses 47732.4.7 Parameter Initialization 47732.4.8 Special Function Organization

Blocks 47732.4.9 Error Handling 477

33 Block Libraries 480

33.1 Organization Blocks 480

33.2 System Function Blocks 481

33.3 IEC Function Blocks 484

33.4 S5-S7 Converting Blocks . . . . 485

33.5 TI-S7 Converting Blocks . . . . 486

33.6 PID Control Blocks 487

33.7 Communication Blocks 487

33.8 Miscellaneous Blocks 487

34 STL Operation Overview . . . 488

34.1 Basic Functions 488

34.1.1 Binary Logic Operations . . . . 48834.1.2 Memory Functions 48934.1.3 Transfer Functions 48934.1.4 Timer Functions 48934.1.5 Counter Functions 489

34.2 Digital Functions 489

34.2.1 Comparison Functions 48934.2.2 Math Functions 49034.2.3 Arithmetic Functions 49034.2.4 Conversion Functions 49034.2.5 Shift Functions 49034.2.6 Word Logic Operations 490

34.3 Program Flow Control 491

34.3.1 Jump Functions 49134.3.2 Master Control Relay 49134.3.3 Block Functions 491

34.4 Indirect Addressing 491

35 SCL Statement and Function

Overview 492

35.1 Operators 492

35.2 Control Statements 492

35.3 Block Calls 492

35.4 SCL Standard Functions 493

35.4.1 Timer Functions 493

35.4.2 Counter Functions 49335.4.3 Conversion Functions 49335.4.4 Math Functions 49435.4.5 Shift and Rotate 494

Index 495

Abbreviations 503

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