Siemens Module B3 manual

A utomation and Drive s - SCE T I A Training Document Page 1 of 64 Module Training Document for Comprehensive Automation Solutions Totally Integrated Automation (T I A) MODULE B3 Control Engineering with STEP 7 B3 Issued: 02/2008 Control Engineering with STEP 7[...]

A utomation and Drive s - SCE T I A Training Document Page 2 of 64 Module This document has been written by Siemens AG for tr aining purposes for the project entitled "Siemens Automation Cooperates with Education (SCE)". Siemens AG accepts no responsibility fo r the correctness of the contents. Transmission, use or reproduction of this do[...]

A utomation and Drive s - SCE T I A Training Document Page 3 of 64 Module Table of Contents PAGE 1. Preface 5 2. Fundamentals of Control Engineering 7 2.2 Components of a Control Loop 8 2.3. Characteristics 11 2.4 Step Function for Examining Controlled Systems 12 2.5. Self-Regulating Processes 13 2.5.1. Proportional Controlled System without Time D[...]

A utomation and Drive s - SCE T I A Training Document Page 4 of 64 Module The follow ing symbols prov ide a guide through this B3 module: Information Programming Exercise Example Notes B3 Issued: 02/2008 Control Engineering with STEP 7[...]

A utomation and Drive s - SCE T I A Training Document Page 5 of 64 Module 1. PREFACE Preface Fundamentals Discontinuous Acti on Controllerr Controller Block (S)FB41 Setting the System Appendix In terms of its contents, Module B3 is part of the teaching unit entitled "Additional Functions of STEP 7 Programming' . Basics of STEP 7 Programmi[...]

A utomation and Drive s - SCE T I A Training Document Page 6 of 64 Module Hardw are and softw are required 1 PC, operating system Windows 2000 Professional starting with SP4/XP Professional starting with SP1/Server 2003 with 600MHz and 512RAM, free hard disk storage 650 to 900 MB, MS Internet Explorer 6.0 2 Software STEP7 V 5.4 3 MPI interface for [...]

A utomation and Drive s - SCE T I A Training Document Page 7 of 64 Module 2. FUNDAMENTALS OF CONTROL ENGINEERING 2.1 Tasks of Control Engineering "Closed loop control is a process where the va lue of a variable is established and maintained continuously through intervention based on measurements of this variable. This creates a sequence that t[...]

A utomation and Drive s - SCE T I A Training Document Page 8 of 64 Module 2.2 Components of a Control Loop Below, the basic terminology of cont rol engineering is explained in detail. First, an overview shown in the diagram below: Measuring Device Controlled System Final Control Element Actuator Controlling Element Comparing Element Controller 1. T[...]

A utomation and Drive s - SCE T I A Training Document Page 9 of 64 Module 4. The Disturbance Variable z The disturbance variable is the variable that unint entionally influences the controlled variable, and moves it from the current setpoint value. A fix ed setpoint control is necessary, for example, because a disturbance variable exists. For the h[...]

A utomation and Drive s - SCE T I A Training Document Page 10 of 64 Module 8. The Actuator The actuator is the “executing organ“, so to speak, of the control system. In t he form of the controller output variable, the controlling element provides the actuator with information as to how the controlled variable is to be influenced, and implements[...]

A utomation and Drive s - SCE T I A Training Document Page 11 of 64 Module 2.3. Characteristics Controlled systems in which a new constant output value sets itself after a certain time has passed are called 'self-regulating process’. The relationship of the output variables to the i nput variables in the steady state results in a characteris[...]

A utomation and Drive s - SCE T I A Training Document Page 12 of 64 Module 2.4 Step Function for Examining Controlled Systems To examine the behavior of contro lled systems, controllers and cont rol loops, a uniform function is used for the input signal: the step function. D epending on whether a control loop element or the entire control loop is e[...]

A utomation and Drive s - SCE T I A Training Document Page 13 of 64 Module 2.5. Self-Regulating Processes 2.5.1. Proportional Controlled System without Time Delay The controlled system is called P-sy stem for short. Abrupt change of the input variable for Proportional coefficient for a manipulated variable change Proportional value for a disturbanc[...]

A utomation and Drive s - SCE T I A Training Document Page 14 of 64 Module 2.5.2. Proportional Controlled System with a Time Delay The controlled system is called P-T1 system for short. Solution of the differential equation for a step function at the input (step response) Time constant Differential equation for a general input signal Preface Fundam[...]

A utomation and Drive s - SCE T I A Training Document Page 15 of 64 Module 2.5.3 Proportional Controlled System with Tw o Time Delays The controlled system is called P-T2 system for short. Figure: Jump Response of the P-T2 system Tu: Delay time Tg: Transition time The system consists of the reaction-free series connection of two P- T1 systems that [...]

A utomation and Drive s - SCE T I A Training Document Page 16 of 64 Module 2.5.4 Proportional Controlled System with n Time Delays The controlled system is called P-Tn system for short. The time response is described with a differential equation of the nth degree. The characteristic of the step response is similar to that of the P-T2 system. The ti[...]

A utomation and Drive s - SCE T I A Training Document Page 17 of 64 Module 2.6 Controlled Systems without Inherent Regulation The controlled variable continues to grow after a fault, without aiming for the high range value. Example: Level Control In the case of a container with a drain whose in flow volume stream and outflow volume stream are the s[...]

A utomation and Drive s - SCE T I A Training Document Page 18 of 64 Module 2.7 Types of Controllers 2.7.1 Tw o Position Controllers The essential feature of two position controllers consists of their know ing only two modes: “On“ and “Off“ -which makes them the simplest type of c ontroller. Two-position controllers are used primarily when a[...]

A utomation and Drive s - SCE T I A Training Document Page 19 of 64 Module The diagram below shows a two position controller: Controlled Variable Time Switch-On Value Manipulated Variable Time Setpoint Switch-Off Value Hysteresis Preface Fundamentals Discontinuous Action Controller Controller Block (S)FB41 Setting the System Appendix B3 Issued: 02/[...]

A utomation and Drive s - SCE T I A Training Document Page 20 of 64 Module 2.7.2 Three Position Controllers The three position controllers represent the se cond important class of discrete controllers. The difference regarding the two position controllers consists in the following: The controller output can handle three different values: positive i[...]

A utomation and Drive s - SCE T I A Training Document Page 21 of 64 Module 2.7.3 Basic Types of Continuous Controllers The discrete controllers just discussed have, as mentioned before, the advantage of being simple. The controller itself as well as the actuator and the final control element are of a simpler nature and thus less expensive than for [...]

A utomation and Drive s - SCE T I A Training Document Page 22 of 64 Module 2.7.3.1 Proportional Controllers (P-Controller) In the case of a P-controller, the controller output y is always proportional to the recorded system deviation (y ~ e). The result is that a P-controller responds to a system deviation without a delay, and generates a controlle[...]

A utomation and Drive s - SCE T I A Training Document Page 23 of 64 Module The figure below shows the performance of the P-controller: Time System Deviation Setpoint A ctual Value Controlled Variable The advantages of this controller type are, on the one hand, its simplicity (the electronic implementation can, in the simplest case, consist of merel[...]

A utomation and Drive s - SCE T I A Training Document Page 24 of 64 Module 2.7.3.2 Integral Action Controllers (I- Controller) Integrating controllers are used to completely corre ct system deviations at every operating point. As long as the system deviation is not equal to zero , the amount of the controller output changes. Only when the reference[...]

A utomation and Drive s - SCE T I A Training Document Page 25 of 64 Module 2.7.3.3 PI Controllers In practice, the PI controller is a controller type that is used very often. It consists of the parallel connection of a P-controller and an I-controller. When laid out correctly, it combines the advantages of both controller types (stable and fast, no[...]

A utomation and Drive s - SCE T I A Training Document Page 26 of 64 Module 2.7.3.4 Derivative Action Controllers (D-Controller) The D-controller generates its controller output from the rate of change of the system deviation, and not -like the P-controller- from its amplitude. For t hat reason, it still responds considerably faster than the P-contr[...]

A utomation and Drive s - SCE T I A Training Document Page 27 of 64 Module 2.8 Objectives for Controller Adjustment For a satisfactory control result , selecting a su itable controller is an important aspect. However, even more important is the setting of the suitable controller parameters Kp, Tn and Tv that have to be adjusted to the controlled sy[...]

A utomation and Drive s - SCE T I A Training Document Page 28 of 64 Module - Note down the Kp value that has been set as the critical proportional coefficient. - Specify the duration of a complete oscillation as Tkrit, perhaps with a stop watch by generating the arithmetical mean over several oscillations. - Multiply the values of Kp,krit and Tkrit[...]

A utomation and Drive s - SCE T I A Training Document Page 29 of 64 Module 2.9 Digital Controllers So far, mainly analog controllers were discussed; t hat is, such controllers that derive the controller output variable -also in an analog way- from the existing system deviation that exists as analog value. We are already familiar with the diagram of[...]

A utomation and Drive s - SCE T I A Training Document Page 30 of 64 Module The diagram below shows the lay out of a digital controller: ADC System Digital Controller DAC Comparing Element However, the digital conversion of the contro ller has not only advantages; this conversion also entails various problems. For that reason, some variables have to[...]

A utomation and Drive s - SCE T I A Training Document Page 31 of 64 Module 3. DISCONTINUOUS ACTION CONTROLLE R AS TWO POSITION CONTROLLER 3.1 Function and Problem Description A process value (for example, the level) is to be kept as constant as possible with a discontinuous action controller. The output voltage at a digital output of the PL C gener[...]

A utomation and Drive s - SCE T I A Training Document Page 32 of 64 Module Structogram A structogram shows the rough structure of a pr ogram plan. The structogram below shows the possible structure of a program for a two position controller. First, a scan is made whether t he controller is switched on. If it is switched off, only the program is ex [...]

A utomation and Drive s - SCE T I A Training Document Page 33 of 64 Module Assignment List: Symbol: Address: Comment Start I 1.3 Button Start Stop I 1.4 Button Stop AI_Level_Actual PEW 128 Analog input for the level sensor AI_Level_Setpoint PEW 130 Analog input for the setpoint selection AI_Level_Act_Norm MD 20 Normalized value for the level AI_Lev[...]

A utomation and Drive s - SCE T I A Training Document Page 34 of 64 Module 3.2 Possible Solution for the PLC Program: Analog Value Processing Network 1: Enter and normalize analog value of actual level "AI_Level_Actual“ "AI_Level_Actual_Norm“ "AI_Level_Setp“ N etwork 2 : Enter and normalize analog value of setpoint level t itL [...]

A utomation and Drive s - SCE T I A Training Document Page 35 of 64 Module Network 4 : Calculation of half differential X1 = Xs/2 "AI_Fill_Setp_Norm“ N etwork 5: Calculation of the low operating point Xu = w – X1 N etwork 6 : ACTUAL VALUE x less than low operating point? D24/AI_Fill_Setp_Norm/Norm.value for level setpoint "AI_Fill_Act[...]

A utomation and Drive s - SCE T I A Training Document Page 36 of 64 Module Network 9 : Reset values exit: "AI_Fill_Actual_Norm“ "AI _ Fill _ Setp _ Norm "Pump“ "Pump“ "Display_ON“ "Display _ ON“ **************************************************************************************************************** Ne[...]

A utomation and Drive s - SCE T I A Training Document Page 37 of 64 Module 4. CONTROLLER BLOCK (S)FB41 "CONT_C" AS SOFTWARE PID CONTROLLER IN STEP 7 4.1 Task Definition for PID Standard Controller In this B3 module, the startup of a PID controller in SIMATIC S7 is demonstrated. The output value of the controlled system is to be kept const[...]

A utomation and Drive s - SCE T I A Training Document Page 38 of 64 Module Assignment List: Symbol: Address: Comment AI_w PEW 128 Analog input setpoint generator 0…10V AI_X PEW 130 Analog input sensor actual value 0…10V AO_Y PAW 128 Analog output manipulated variable 0 … 10V M_w MD40 Internal setpoint (floating point number normalized) Functi[...]

A utomation and Drive s - SCE T I A Training Document Page 39 of 64 Module 4.2 (S) FB 41 “CONT_C“ (S)FB 41 "CONT_C“ (continuous controller) is us ed for controlling technical processes with continuous input and output variables on the PLC SIMATIC S7. By means of parameter assignments, you can switch on or switch off subfunc tions of the [...]

A utomation and Drive s - SCE T I A Training Document Page 40 of 64 Module Starting Up the Softw are PID Controller (S)FB41 "CONT_C" w ith STEP 7 A SIMATIC S7-300 is programmed as a PID controlle r with the software STEP 7. This provides the user with a uniform configuring tool for central as well as distributed configurations. Here, only[...]

A utomation and Drive s - SCE T I A Training Document Page 41 of 64 Module 3. Generate a new project, select a path and assign a project name ( → User projects → PID_Control → OK) Enter project name Cick 'OK' Select storage location (path) Select 'User Projects’ 4. Insert the SIMATIC 300 station ( → Insert → Station → S[...]

A utomation and Drive s - SCE T I A Training Document Page 42 of 64 Module 5. Highlight 'SIMATIC 300 Station(1)’. Click on 'SIMATIC 300 Station(1)' 6. Open configuring tool fo r the hardware configuration ( → Edit → Open object) Click on 'Open object’ Preface Fundamentals Di scontinuous Action Controllerr Controller Bloc[...]

A utomation and Drive s - SCE T I A Training Document Page 43 of 64 Module 7. Open the hardware catalog. Here, all racks, modules, and interface modules fo r configuring your hardware, are provided arranged in the directories: PROFIBUS-D P, SIMATIC 300, SIMA TIC 400 and SIMATIC PC Based Control. Click on the symbol for 'HW catalog’ 8. Insert[...]

A utomation and Drive s - SCE T I A Training Document Page 44 of 64 Module 9. From the hardware catalog, all modules that are plugged inserted in your real rack can now be selected and inserted in the confi guration table. To this end, you have to click on the name of the respective module, hold the mouse key and dr ag the module to a line in the c[...]

A utomation and Drive s - SCE T I A Training Document Page 45 of 64 Module 10. Note down the addresses of the IO modules (addresses are assigned automatically and tied to the slot ). For our example, change the addresses to the values PEW 128 and PAW 128. Save the configuration table and load it to the PLC (key switch on CPU has to be on Stop!) Pre[...]

A utomation and Drive s - SCE T I A Training Document Page 46 of 64 Module 12. Insert organization block. ( → Insert → S7 Block → Organization block) Click on 'Organization block’ 13. Assign OB35 as name of block.( → OB35 → OK) Note: OB35 is a so-called 'Time interrupt OB’ and ensures a constant cycle for calling the PID con[...]

A utomation and Drive s - SCE T I A Training Document Page 47 of 64 Module 14. In the hardware configuration, at Properties of the CPU, a fixed cycle time can be set for executing OB35. However, this cycle time should not be selected too short. It has to be ensured that all blocks called from OB35 can be processed within this ti me, and if OB1 is u[...]

A utomation and Drive s - SCE T I A Training Document Page 48 of 64 Module 16. With ‘LAD, STL, and FBD – Program S7 Blo cks’, you now have an editor that allows you to edit your STEP7 program accordingly. To this end, OB35 has already been opened with the first network. To generate your first operations, you have to high light the first netwo[...]

A utomation and Drive s - SCE T I A Training Document Page 49 of 64 Module 17. The setpoint value, the actual value and the manipulated variable now have to be wired to process values as follows. Cycle time: Time between the block call. Should correspond to the time that is set in OB 35. LMN PER: Manipulated variable output at analog out p ut SP IN[...]

A utomation and Drive s - SCE T I A Training Document Page 50 of 64 Module 18. Save and load OB35 (CPU’s key switch is on Stop!) 19. In ‘SIMATIC Manager’, highlight block DB41 and load to the PLC. (CPU’s key switch is on Stop!) Preface Fundamentals Di scontinuous Action Controllerr Controller Block (S)FB41 Setting the System Appendix Click [...]

A utomation and Drive s - SCE T I A Training Document Page 51 of 64 Module 20. Call the tool Assign parameters to the PID control ( → Start → Simatic → STEP 7 → Parameterize PID Control) Click on ‘Parameterize PID Control’ Preface Fundamentals Di scontinuous Action Controllerr Controller Block (S)FB41 Setting the System Appendix B3 Issu[...]

A utomation and Drive s - SCE T I A Training Document Page 52 of 64 Module 21. Open data block ( → File → Open → Online → Select data block; for example, DB41 → OK). Click on ‘Open’ Switch block to the online mode DB 41 auswählen Click on ‘OK’ Preface Fundamentals Di scontinuous Action Controllerr Controller Block (S)FB41 Setting[...]

A utomation and Drive s - SCE T I A Training Document Page 53 of 64 Module 22. The PID controller can now be parameterized with the tool Parameterize PID Control . Then, the DB is saved ( → Save) and loaded to the PLC ( → Load). Now, a curve plotter can be started in order to monitor the performance of the controlled system. Preface Fundamental[...]

A utomation and Drive s - SCE T I A Training Document Page 54 of 64 Module 5. SETTING CONTROLLED SYSTEMS 5.1 General Below, setting controlled sy st ems is discuss ed, using a PT2 system as an example. T u -T g Approximation The basis for the methods according to Ziegler-Nichols and according to Chien, Hrones and Reswick is the T u -T g approximati[...]

A utomation and Drive s - SCE T I A Training Document Page 55 of 64 Module 5.2 Setting the PI-Controller according to Ziegler-Nichols By experimenting with P-T 1 -T L systems, Ziegler and Nichols have found the following optimum controller settings for fixed setpoint control: K S T u T g K PR = 0, 9 T N = 3,33 T u 0.9 3.3 In general, we get disturb[...]

A utomation and Drive s - SCE T I A Training Document Page 56 of 64 Module • For setpoint characteristic: Preface Fundamentals Di scontinuous Action Controller Controller Block (S)FB41 Setting the System Appendix K S T u T g K PR = 0, 35 T N = T g 1,2 aperiodi scher Ei nschw ing v organg mi t k ür z este - r Dauer K S T u T g K PR = 0,6 Apriodic[...]

A utomation and Drive s - SCE T I A Training Document Page 57 of 64 Module 5.4 Exercise Example To accommodate the system step response, a fe w modifications have to be made in OB 35 and DB41. The following steps have to be performed for this: Save your old project under a new name, and change the wiring of (S)FB 41 as follows: 1. With STEP7, speci[...]

A utomation and Drive s - SCE T I A Training Document Page 58 of 64 Module Solution of the PLC program: Network 1 : Call PID Controller Wiring the manual value to thevalue 0 or 100% of the manipulated value (Refer to NW 2 and NW 3) Network 2 : Default Manipulated value 100% Network 3 : Default Manipulated value 0% Preface Fundamentals Di scontinuou[...]

A utomation and Drive s - SCE T I A Training Document Page 59 of 64 Module Then, the system step response is recorded with the curve plotter from 0 to 100%. For systems that tend to overshoot, 90% should be assigned as step value. Tu Tg Turning Point Setpoint System step response for T u -T g approximation After the inflectional tangent is drawn in[...]

A utomation and Drive s - SCE T I A Training Document Page 60 of 64 Module 6. APPENDIX Diagram of the controller block: Preface Fundamentals Discontinuous Action Controller Controller Block (S)FB41 Setting the System Appendix B3 Issued: 02/2008 Control Engineering with STEP 7[...]

A utomation and Drive s - SCE T I A Training Document Page 61 of 64 Module Input Parameters Parameter Data Type Value Range Default Description COM_RST BOOL FALSE COMPLETE RESTART. The block has a complete restart routine that is processed if the input is set to "Complete restart". MAN_ON BOOL TRUE MANUAL VALUE ON / Switch on manual opera[...]

A utomation and Drive s - SCE T I A Training Document Page 62 of 64 Module Parameter Data Ty pe Value Range Default Description CYCLE TIME >= 1 ms T#1s SAMPLE TIME. The time between block calls has to be constant. T he input "Sample time" indicates the time between block calls. SP_INT REAL -100.0...+100.0% 0.0 INTERNAL SETPOINT. The in[...]

A utomation and Drive s - SCE T I A Training Document Page 63 of 64 Module Parameter Data Type Value Range Default Description LMN_HLM REAL LMN_LLM... +100.0 % or phys. variable 2 100.0 MANIPULATED VALUE HIGH LIMIT. The manipulated value is always limited to a high and a low limit. "Manipulated value high limit" indicates the high limit. [...]

A utomation and Drive s - SCE T I A Training Document Page 64 of 64 Module Output Parameters: Parameter Data Type Value Range Default Description LMN REAL 0.0 MANIPULATED VALUE. At the output "Manipulated value", the effectively active manipul ated value is read out in the floating point format. LMN_PER WORD W#16#0000 MANIPULATED VALUE PE[...]