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Industry Automation and Drive Technologies - SCE
SEQUENTIAL FUNCTION CHART
OBJECTIVE
The students will be able to successfully implement sequential controls using step
sequences. The students understand the structure and effect of step sequences, and are
introduced to corresponding design methods. Knowledge about operating modes and
protective measures is expanded for sequential controls. The students understand the
interaction between the programs for basic automation and the sequen
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Industry Automation and Drive Technologies - SCE THEORY CONTINUOUS AND SEQUENTIAL CONTROLS Within the scope of basic automation, different logic control systems are developed that implement a limited, clearly defined function. The functions continuously process input signals and generate corresponding output signals. By means of different control signals, the functions can also be activated and parameterized. To implement complex process sequences -for example, manufacturing recipes
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Industry Automation and Drive Technologies - SCE Loops within the step sequence occur when by sequencing several steps a cyclical run within a sequence is possible. The sequence loop represents a special case of a loop where all steps are run cyclically. Another option for structuring step sequences is jumps. When a jump mark is reached, processing continues with the step to which the jump mark points. Jumps within the step sequence can also result in loops. Since such a structure
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Industry Automation and Drive Technologies - SCE A particular control engineering problem is the possibility to generate -by unfavorably using jumps and branches- faulty step sequences. We are distinguishing three possible cases. – Uncertain sequence: A step sequence contains a structure whose availability is not ensured through the defined sequential performance. – Partially stuck: A step sequence contains an internal loop that is not exited. Although the steps within this loop are ex
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Industry Automation and Drive Technologies - SCE DESIGN OF SEQUENCE CONTROLS There are numerous formal design methods for sequence controls. In practice, however, particularly the state diagrams and Petri’s network have proven themselves. A state diagram is a connected, oriented diagram. States are represented as circles and the state transitions as arrows that connect exactly two states. In a state diagram, always exactly one state is active at a time. The states can be linked to c
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Industry Automation and Drive Technologies - SCE PROTECTION FUNCTIONS AND OPERATING MODES IN SEQUENCE CONTROLS Just as for the individual drive functions, adequate protection functions and operating modes have to be implemented for sequence controls. It has to be possible to operate sequence controls manually if there is a fault. To this end, corresponding operating modes have to be provided for in the control. – Automatic mode: The action of the step sequence is executed if the preced
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Industry Automation and Drive Technologies - SCE subsequent transition of an active step automatically sets an operator prompt (O = Operator). – Switching Mode T or O: The sequence control is running process controlled or operator controlled. The transition is enabled either through an operator command or a step enabling condition that was met. – Switching Mode T and O: The sequence control is running process controlled and operator controlled. The transition is enabled only based on
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Industry Automation and Drive Technologies - SCE STEP BY STEP INSTRUCTIONS TASK Based on the recipe in the chapter 'Process Description’ we are setting up and programming an SFC step sequence. For this chapter, we reduced the recipe to the following sequence: 1. First, 350ml are to be drained from educt tank =SCE.A1.T1-B003 to reactor =SCE.A1.T2-R001. 2. When reactor =SCE.A1.T2-R001 is filled, the liquid it contains is to be heated to 25°C and the stirrer is to be switched on. 3.
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Industry Automation and Drive Technologies - SCE PROGRAMMING 1. To start, we are setting up a new SFC in the plant view in the folder ’A1_multipurpose_ plant’. ( A1_multipurpose_pant Insert New Object SFC) TIA Training Manual Page 9 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 2. Next, we are selecting the SFC properties. ( SFC(1) Object Properties) 3. Under General, we change the name to ’SFC_Produkt01’. ( General SFC_Produkt01) TIA Training Manual Page 10 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 4. We are keeping the operating parameters; they can be changed later in the online mode ( AS Operating parameters) 5. Regarding the tab OS it is important that the checkmark is set so that the SFC will be available later in visualization. ( OS Transfer chart to the OS for visualization) TIA Training Manual Page 11 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 6. Under the tab Version, we accept all parameters with OK. ( Version OK) 7. Now, with a double click, we open the step sequence ’SFC_Produkt01’ in the SIMATIC Manager. ( SFC_product01) TIA Training Manual Page 12 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 8. In the SFC editor, it is now possible to set up the sequence control with the following symbols from the tool bar. Button Switch on Select Button Insert Step and Transition Button Insert parallel branch Button Insert alternative branch Button Insert loop Button Insert jump Button Insert text field TIA Training Manual Page 13 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 9. We need additional steps and transitions for our task. To insert both, we select the button and then select the location where we want to insert them. ( ) TIA Training Manual Page 14 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 10. After we inserted five steps and transitions in this way, we click on the symbol to edit normally again. ( ) ! Note: Step and transition numbering is of no impotance for the sequence in which the step sequence is processed. TIA Training Manual Page 15 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 11. Now, we first want to be able to change the properties of a step. Right click on the step and then select Object Properties. ( 3 Object Properties) 12. For greater clarity, each step is assigned a name in the object properties. ( eductB003toR001 Close) TIA Training Manual Page 16 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 13. As for the steps, for the transitions also the properties have to be changed. Right click on the transition and then select Object Properties. ( 1 Object Properties) 14. Here also, first only the name is changed. ( Init_OK Close) TIA Training Manual Page 17 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 15. Repeat the previous steps until our SFC looks like this. It is important to enter at the step ’hold 25°C stir’ also the minimum execution time of 10 seconds. ( T#10s) TIA Training Manual Page 18 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 16. Now we have to implement the actual function of the step sequence. We start by double clicking on the step ’START’. ( START) 17. To establish logic operations with the CFCs or symbols, we are selecting the first field and then click on ’Browse’. ( Browse) TIA Training Manual Page 19 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
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Industry Automation and Drive Technologies - SCE 18. Then, in a selection window in the familiar clearly laid out plant view we select the connection of a desired block. ( SCE_factory A1_multipurpose_plant T1_educt_tanks A1T1S003 A1T1S003 Pump_A1T1S003 AUT_ON_OP) TIA Training Manual Page 20 of 41 Module P01_07 Status: 12/2010 PCS 7 for Universities
