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Book Review: Automating with STEP 7 in LAD and FBD by Hans Berger
The world would be a better place, at least for the Siemens PLC programmer, if there was a good instructional book available. Unfortunately this book by Hans Berger is not it. It’s definitely not a book for beginners and I couldn’t even recommend it for the more experienced programmer. The only thing it might be good for is reference material in the later sections. I’ve been programming PLCs for a number of years but even with that experience the Siemens ‘way’ of programming is quite different. So it’s quite natural to go looking for more instruction. The manuals are either to simplistic or overly technical. It’s really left a gap for some good instruction on the why’s and how’s of programming in the Siemens world. This book only looks to rehash the content in the manual without providing any additional insights. Bad EnglishThe major problem with this book is the way it is written. The English is bad. The likely reason for this is a bad translation from its original German. If you like eating moth balls then you’ll enjoy it because it’s very dry reading. Technical reading is not often fun but it shouldn’t have to be this excruciating. It’s one of those books where you have to read over a section a couple of times before something may sink in. Here’s a typical example from the text.
Most of the sentences in the book are like these. There’s an excessive amount of “you can do this” or “you can do that” but with little explanation of why. The book also suffers from a lot of non-explained technical terms. For instance, here’s another all too frequent difficult paragraph.
Admittedly it’s hard to write a book about PLCs without experiencing the “chicken and egg” problem. Which explanation comes first? Some books handle it better then others but Berger has a difficult time introducing new subjects. What? No Pretty Pictures?What makes a good book are often the figures, illustrations and charts accompanying the text. I felt in this area the book was also lacking. There are plenty of graphics (2-D, black and white) but they are either not too helpful or overly complicated. Most of the tables seem to be pulled from the manuals. The thing I found most frustrating was the lack of screen shots. For a book specifically dealing with a programming environment I would have expected more. Basically from page 37 to 244 (309 total) there are no screen shots. An example where I thought it would be very appropriate to add a screen was the “Block Function” section where the example looks like this… 
Isn’t that just screaming for a screen shot? Lack of ExercisesAnother feature missing from the book are exercises and testing. So for an educator looking to use this as a classroom textbook they will have to come up with their own material. There are examples in the book (and on an accompanying floppy disk) but they also suffer from long technical explanations with no pictures followed by a code dump. This makes the examples hard to follow. It would have been a lot better to intersperse the comments throughout the ladder and FBD to break it up so that a student could make more sense of the code line by line. ConclusionsThe bottom line is that we would recommend not wasting your money on this book. The major disadvantage is a difficult writing style making it very dry and confusing. The illustrations and tables add nothing to the text. Last of all, there is a complete lack of exercises and tests. You’re best bet is to stick with the manuals and some of the other online helps found on the Siemens website.
Table of ContentsIntroduction1 SIMATIC S7?300/400 Programmable Controller 1.1 Structure of the Programmable Controller 1.1.1 Components 1.1.2 S7?300 Station 1.1.3 S7?400 Station 1.1.4 CPU Memory Areas 1.1.5 Memory Card 1.1.6 System Memory 1.2 Distributed I/0 1.2.1 DP Master System 1.2.2 DP Master 1.2.3 DP Slaves 1.2.4 Connection to PROFIBUS?PA 1.2.5 Connection to AS?Interface 1.2.6 Connection to a Serial Interface 1.3 Communications 1.3.1 Introduction 1.3.2 Subnets 1.3.3 Communications Services 1.3.4 Connections 1.4 Module Addresses 1.4.1 Signal Path 1.4.2 Slot Address 1.4.3 Module Start Address 1.4.4 Diagnostics Address 1.4.5 Address for Bus Nodes 1.5 Address Areas 1.5.1 User Data Area 1.5.2 Process Image 1.5.3 Bit Memory
2 STEP 7 Programming Software2.1 STEP 7 Basic Package 2.1.1 Installation 2.1.2 Authorization 2.1.3 SIMATIC Manager 2.1.4 Projects and Libraries 2.1.5 Online Help 2.2 Editing Projects 2.2.1 Creating Projects 2.2.2 Managing, Rearranging and Archiving 2.2.3 Project Versions 2.3 Configuring Stations 2.3.1 Arranging Modules 2.3.2 Addressing Modules 2.3.3 Parameterizing Modules 2.3.4 Networking Modules with MPI 2.4 Configuring the Network 2.4.1 Configuring the Network View 2.4.2 Configuring a DP Master System with the Network Configuration 2.4.3 Configuring Connections 2.4.4 Loading the Connection Data 2.5 Creating the S7 Program 2.5.1 Introduction 2.5.2 Symbol Table 2.5.3 Program Editor 2.5.4 Updating or generating source files 2.5.5 Address Priority 2.5.6 Reference Data 2.6 Online Mode 2.6.1 Connecting a PLC 2.6.2 Protecting the User Program 2.6.3 CPU Information 2.6.4 Loading the User Program into the CPU 2.6.5 Block Handling 2.7 Testing the Program 2.7.1 Diagnosing the Hardware 2.7.2 Determining the Cause of a STOP 2.7.3 Monitoring and Modifying Variables 2.7.4 Forcing Variables 2.7.5 Enabling Peripheral Outputs 2.7.6 LAD/FBD Program Status
3 SIMATIC S7 Program3.1 Program Processing 3.1.1 Program Processing Methods 3.1.2 Priority Classes 3.1.3 Specifications for Program Processing 3.2 Blocks 3.2.1 Block Types 3.2.2 Block Structure 3.2.3 Block Properties 3.3 Programming Code Blocks 3.3.1 Generating blocks 3.3.2 Editing LAD Elements 3.3.3 Editing FBD Elements 3.4 Programming Data Blocks 3.4.1 Creating Blocks 3.4.2 Types of Data Blocks 3.4.3 Block Window 3.5 Variables, Constants and Data Types 3.5.1 General Remarks Concerning Variables 3.5.2 Addressing Variables 3.5.3 Overview of Data Types 3.5.4 Elementary Data Types 3.5.5 Complex Data Types 3.5.6 Parameter Types 3.5.7 User Data Types
4 Binary Logic Operations4.1 Series and Parallel Circuits (LAD) 4.1.1 NO Contact and NC Contact 4.1.2 Series Circuits 4.1.3 Parallel Circuits 4.1.4 Combinations of Binary Logic Operations 4.1.5 Negating the Result of the Logic Operation 4.2 Binary Logic Operations (FBD) 4.2.1 Elementary Binary Logic Operations 4.2.2 Combinations of Binary Logic Operations 4.2.3 Negating the Result of the Logic Operation 4.3 Taking Account of the Sensor Type
5 Memory Functions5.1 LAD Coils 5.1.1 Single Coil 5.1.2 Set and Reset Coil 5.1.3 Memory Box 5.2 FBD Boxes 5.2.1 Assign 5.2.2 Set and Reset Box 5.2.3 Memory Box 5.3 Midline Outputs 5.3.1 Midline Outputs in LAD 5.3.2 Midline Outputs in FBD 5.4 Edge Evaluation 5.4.1 How Edge Evaluation Works 5.4.2 Edge Evaluation in LAD 5.4.3 Edge Evaluation in FBD 5.5 Binary Scaler 5.5.1 Solution in LAD 5.5.2 Solution in FBD 5.6 Example of a Conveyor Control System
6 Move Functions6.1 General 6.2 MOVE Box 6.2.1 Processing the MOVE Box 6.2.2 Moving Operands 6.2.3 Moving Constants 6.3 System Functions for Data Transfer 6.3.1 ANY Pointer 6.3.2 Copy Data Area 6.3.3 Uninterruptible Copying of a Data Area 6.3.4 Fill Data Area
7 Timers7.1 Programming a Timer 7.1.1 General Representation of a Timer 7.1.2 Starting a Timer 7.1.3 Specifying the Duration of Time 7.1.4 Resetting A Timer 7.1.5 Checking a Timer 7.1.6 Sequence of Timer Operations 7.1.7 Timer Box in a Rung (LAD) 7.1.8 Timer Box in a Logic Circuit (FBD) 7.2 Pulse Timer 7.3 Extended Pulse Timer 7.4 On?Delay Timer 7.5 Retentive On?Delay Timer 7.6 Off?Delay Timer 7.7 IEC Timers 7.7.1 Pulse Timer SFB 3 TP 7.7.2 On?Delay Timer SFB; 4 TON 7.7.3 Off?Delay Timer SFB 5 TOF
8 Counters8.1 Programming a Counter 8.2 Setting and Resetting Counters 8.3 Counting 8.4 Checking a Counter 8.5 IEC Counters 8.5.1 Up Counter SFB 0 CTU 8.5.2 Down Counter SFB I CTD 8.5.3 Up/down Counter SFB 2 CTUD 8.6 Parts Counter Example
Digital Functions9 Comparison Functions9.1 Processing a Comparison Function 9.2 Description of the Comparison Functions
10 Arithmetic Functions10.1 Processing an Arithmetic Function 10.2 Calculating with Data Type INT 10.3 Calculating with Data Type DINT 10.4 Calculating with Data Type REAL
11 Mathematical Functions11.1 Processing a Mathematical Function 11.2 Trigonometric Functions 11.3 Arc Functions 11.4 Miscellaneous Mathematical Functions
12 Conversion Functions12.1 Processing a Conversion Function 12.2 Conversion of INT and DINT Numbers 12.3 Conversion of BCD Numbers 12.4 Conversion of REAL Numbers. 12.5 Miscellaneous Conversion Functions
13 Shift Functions13.1 Processing a Shift Function 13.1.1 Representation 13.2 Shift 13.3 Rotate
14 Word Logic14.1 Processing a Word Logic Operation 14.2 Description of the Word Logic Operations
Program Flow Control15 Status Bits15.1 Description of the Status Bits 15.2 Setting the Status Bits 15.3 Evaluating the Status Bits 15.4 Using the Binary Result 15.4.1 Setting the Binary Result BR 15.4.2 Main Rung, EN/ENO Mechanism 15.4.3 ENO in the Case of User?written Blocks
16 Jump Functions16.1 Processing a Jump Function 16.2 Unconditional Jump 16.3 Jump if RLO = “l” 16.4 Jump if RLO = “0”
17 Master Control Relay17.1 MCR Dependency 17.2 MCR Area 17.3 MCR Zone 17.4 Setting and Resetting 1/0 Bits
18 Block Functions18.1 Block Functions for Code Blocks 18.1.1 Block Calls: General 18.1.2 Call Box 18.1.3 CALL Coil/Box 18.1.4 Block End Function 18.1.5 Temporary Local Data 18.1.6 Static Local Data 18.2 Block Functions for Data Blocks 18.2.1 Two Data Block Registers 18.2.2 Accessing Data Operands 18.2.3 Opening a Data Block 18.2.4 Special Points in Data Addressing 18.3 System Functions for Data Blocks 18.3.1 Creating a Data Block 18.3.2 Deleting a Data Block 18.3.3 Testing a Data Block
19 Block Parameters19.1 Block Parameters in General 19.1.1 Defining the Block Parameters 19.1.2 Processing the Block Parameters 19.1.3 Declaration of the Block Parameters 19.1.4 Declaration of the Function Value 19.1.5 Initializing Block Parameters. 19.2 Formal Parameters 19.3 Actual Parameters 19.4 "Forwarding" Block Parameters 19.5 Examples 19.5.1 Conveyor Belt Example 19.5.2 Parts Counter Example 19.5.3 Feed Example
Program Processing20 Main Program20.1 Program Organization 20.1.1 Program Structure 20.1.2 Program Organization 20.2 Scan Cycle Control 20.2.1 Process Image Updating 20.2.2 Scan Cycle Monitoring Time. 20.2.3 Minimum Scan Cycle Time, Background Scanning 20.2.4 Response Time 20.2.5 Start Information 20.3 Program Functions 20.3.1 Real?Time Clock 20.3.2 Read System Clock 20.3.3 Run?Time Meter 20.3.4 Compressing CPU Memory 20.3.5 Waiting and Stopping 20.3.6 Multiprocessing Mode 20.4 Communication via Distributed 1/0 20.4.1 Addressing Distributed 1/0 20.4.2 Configuring Distributed 1/0 20.4.3 System Functions for Distributed 1/0 20.5 Global Data Communication 20.5.1 Fundamentals 20.5.2 Configuring GD communication 20.5.3 System Functions for GD Communication 20.6 SFC Communication 20.6.1 Station?Internal SFC Communication 20.6.2 System Functions for Data Interchange Within a Station 20.6.3 Station?External SFC Communication 20.6.4 System Functions for Station External SFC Communication. 20.7 SFB Communication 20.7.1 Fundamentals 20.7.2 Two?Way Data Exchange 20.7.3 One?Way Data Exchange 20.7.4 Transferring Print Data 20.7.5 Control Functions 20.7.6 Monitoring Functions
21 Interrupt Handling21.1 General Remarks 21.2 Hardware Interrupts 21.2.1 Generating a Hardware Interrupt 21.2.2 Servicing Hardware Interrupts 21.2.3 Configuring Hardware Interrupts with STEP 7 21.3 Watchdog Interrupts 21.3.1 Handling Watchdog Interrupts 21.3.2 Configuring Watchdog Interrupts with STEP 7 21.4 Time?of?Day Interrupts 21.4.1 Handling Time?of?Day Interrupts 21.4.2 Configuring Time?of?Day Interrupts with STEP 7 21.4.3 System Functions for Time?of?Day Interrupts 21.5 Time?Delay Interrupts 21.5.1 Handling Time?Delay Interrupts 21.5.2 Configuring Time?Delay Interrupts with STEP 7 21.5.3 System Functions for Time?Delay Interrupts 21.6 Multiprocessor interrupt 21.7 Handling Interrupts
22 Restart Characteristics22.1 General Remarks 22.1.1 Operating Modes 22.1.2 HOLD Mode 22.1.3 Disabling the Output Modules 22.1.4 Restart Organization Blocks 22.2 Power?Up 22.2.1 STOP Mode 22.2.2 Memory Reset 22.2.3 Retentivity 22.2.4 Restart Parameterization 22.3 Types of Restart 22.3.1 START?UP Mode 22.3.2 Cold Restart 22.3.3 Complete Restart 22.3.4 Warm Restart 22.4 Ascertaining a Module Address 22.5 Parameterizing Modules
23 Error Handling23.1 Synchronous Errors 23.2 Synchronous Error Handling 23.2.1 Error Filters 23.2.2 Masking Synchronous Errors 23.2.3 Unmasking Synchronous Errors 23.2.4 Reading the Error Register 23.2.5 Entering a Substitute Value 23.3 Asynchronous Errors 23.4 System Diagnostics 23.4.1 Diagnostic Events and Diagnostic Buffer 23.4.2 Writing User Entries in the Diagnostic Buffer 23.4.3 Evaluating Diagnostic Interrupts 23.4.4 Reading the System Status List
Appendix24 Supplements to Graphic Programming24.1 Block Protection 24.2 Indirect Addressing 24.2.1 Pointers: General Remarks 24.2.2 Area Pointer 24.2.3 DB Pointer 24.2.4 ANY Pointer 24.2.5 "Variable" ANY Pointer 24.3 Brief Description of the "Message Frame Example"
25 Block Libraries25.1 Organization Blocks 25.2 System Function Blocks 25.3 IEC Function Blocks 25.4 S5?S7 Converting Blocks 25.5 TI?S7 Converting Blocks 25.6 PID Control Blocks 25.7 Communication Blocks
26 Function Set LAD26.1 Basic Functions 26.2 Digital Functions 26.3 Program Flow Control
27 Function Set FBD27.1 Basic Functions 27.2 Digital Functions 27.3 Program Flow Control ( categories: )
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