Siemens ST PCS 7 manual Continuous function chart CFC, Sequential function chart SFC

© Siemens AG 2007

Engineering system

ES software

The OS areas and the image hierarchy for process control, as well as the SIMATIC PCS 7 asset management, can be derived from the technological hierarchy. Furthermore, it also forms the basis for the plant-oriented identification of process objects.

Common displays can be positioned in pictures by means of the image hierarchy, and automatically linked to subordinate im- ages. The configuration engineer is only responsible for the cor- rect positioning. Since the number of common display fields and their semantics can be configured, it is also possible to imple- ment customized alarm configurations.

Using the process object view, "Smart Alarm Hiding" can also be configured This function is understood as the dynamic hiding of messages (alarms) of the technological blocks grouped in a plant unit which are of secondary importance depending on the operating state of this unit (startup, service, etc.). Alarms can be displayed or hidden separately for each of the maximum

32 operating states through selection of option boxes in the alarm matrix of the process object view. Although hidden alarms are not signaled visually and audibly, they are still logged and ar- chived as before.

Continuous function chart (CFC)

The CFC editor is the tool for graphical configuration and com- missioning of continuous automation functions. Preengineered function blocks can be positioned, configured and intercon- nected within CFCs with the support of powerful autorouting and integral configuration of HMI messages. Special configuration techniques such as chart-in-chart for implementing hierarchical plans or the multiple usage of chart block types (chart compiled as block type) or SFC types (standardized sequential controls) in the form of instances offer an additional rationalization poten- tial.

When creating a new CFC, a new runtime group with the same name as the chart is created. All the blocks that are subse- quently entered in the chart are automatically added to this run- time group. Each block is therefore already assigned runtime properties when inserting, and these properties can be opti- mized by means of modifications in the runtime editor or by us- ing algorithms.

The algorithm first determines the optimum block sequence sep- arately for each runtime group, and then the optimum sequence of runtime groups.

In addition to convenient editing functions, the scope of CFC functions also includes powerful test and commissioning func- tions as well as individually configurable documentation func- tions.

Standard engineering software

Sequential function chart (SFC)

The SFC editor is used for the graphical configuration and com- missioning of sequential controls for batch production opera- tions. It possesses convenient editing functions as well as pow- erful test and commissioning functions.

Using a sequential control, basic automation functions usually created using CFC are controlled and selectively processed by

means of changes in operating mode and status. Depending on 4 the subsequent use, the sequential controls can be created ei-

ther as a SFC plan or SFC type.

SFC plan

The SFC plan can be used to implement sequential controls which can be applied once and which access several partial ar- eas of the production plant. Each SFC plan contains standard- ized inputs and outputs for status information and for control by the user program or the user. The SFC plan can be positioned and linked as a block in the CFC. The required CFC block con- nections are selected by simple operations and connected to the steps or transitions of the step chains. An ISA 88-conform status manager enables the configuration of up to 8 separate se- quence chains within a single SFC, e.g. for states such as HOLDING or ABORTING, for SAFE STATE or for different operat- ing modes.

SFC type

SFC types are standardized sequential controls which can be applied repeatedly and which access one partial area of the pro- duction plant. They can be organized in libraries, and handled like normal function blocks, i.e. they can be selected from a cat- alog and positioned, interconnected and parameterized as an instance in a CFC plan.

Changes to the original automatically result in corresponding changes in all instances. An SFC type may contain up to

32 sequences. Using the function "Create/update block sym- bols", a block symbol is automatically positioned and intercon- nected in the associated process display for all SFC instances with HMI features.

Sequential function chart

Continuous function chart

Siemens ST PCS 7 · November 2007

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