Configuring SFC Chart Operating State and Mode Displays in SIMATIC PCS 7 WinCC

In SIMATIC PCS 7, displaying the operating mode (MAN or AUTO) and execution state of an SFC Chart on a WinCC process screen requires configuring the chart's Operating State Logic (OSM), placing the SFC in an OS-assigned Plant Hierarchy folder, and compiling the OS with the 'SFC Visualization' option enabled. In WinCC Graphics Designer, connect the standard SFC block icon or status display object to the internal status tags generated by the compiler (@#status and @#mode) rather than attempting manual script polling.

Architecture of SFC Visualization in PCS 7 (SFC Chart vs. SFC Type)

In SIMATIC PCS 7 Operator Stations, sequential processes are visualized using SFC Visualization (@PCS7_SFC_...). When an operator views a plant overview screen, each sequential unit must report its execution state (Ready, Starting, Running, Paused, Holding, Aborting, Completed) and operating mode (Automatic, Manual).

When an engineer creates a new standalone SFC Chart (as opposed to an SFC Type instantiated in a CFC chart) and attempts to animate mode indicators in WinCC, the graphic display often remains unresponsive.

This failure occurs because standalone SFC Charts compile through the shared runtime engine block FB300 (@SFC_RTS). Unlike standard CFC technological blocks that expose OCM (S7_m_c) attributes on individual pins, SFC Charts export their runtime visualization data strictly through the SFC Visualization OS Compiler Extension. If the SFC Chart is not assigned to a Plant Hierarchy folder linked to an OS area, or if the OS compilation was executed without selecting the SFC Visualization subsystem, the necessary WinCC internal structure tags (@<ChartName>#status, @<ChartName>#mode, @<ChartName>#currentstep) are never created in the WinCC tag database.

SFC Runtime State and Mode Tag Structure Matrix

Understand how the SFC compiler encodes operating state and mode variables into WinCC runtime tags:

System Tag SuffixData TypeEncoding FormatMeaning and ValuesTarget Faceplate / Icon Object@<ChartName>#modeBYTE / INTEnumerated Bitmask1 = Manual (MAN), 2 = Automatic (AUT)Mode indicator text and switch buttons@<ChartName>#statusDWORDBit-coded status flagsBit 0: Idle, Bit 1: Starting, Bit 2: Running, Bit 3: HoldingState text (Running, Paused, Aborted)@<ChartName>#currentstepSTRINGAlphanumericText name of currently executing stepActive step display header@<ChartName>#errorBOOLBinary flag1 = Interlock or step execution timeout faultGroup display red flashing fault indicator@<ChartName>#readyBOOLBinary flag1 = Preconditions met; ready for operator startStart button enable condition

Engineering notice: WinCC SFC status tags are managed automatically by the compiler; do not create them manually in Tag Management.

Configuring SFC Operating State Logic (OSM) in SFC Editor

Follow this verified configuration procedure in the engineering system:

Verify SFC Chart Properties:
* Open the target SFC Chart in SFC Editor.
* Select Edit > Properties.
* Under the Operating State Logic (OSM) tab:
- Confirm that the state transition diagram matches plant requirements (e.g., standard ISA-88 state model).
- Verify that Command outputs and Status outputs are enabled.
Assign SFC Chart to Plant Hierarchy (PH):
* In SIMATIC Manager, ensure the SFC Chart resides in a technological hierarchy folder that has an assigned OS picture.
* Right-click the hierarchy folder, select Object Properties > Control and Monitoring Attributes.
* Verify that OCM possible is checked.
Configure Operating Mode Permissions:
* Under SFC properties, verify that Auto/Manual switchover is permitted by operator authorization levels (Level 5 or Level 6).

Compiling SFC Visualization and Linking WinCC Block Icons

To generate the runtime tags and instantiate the visual indicator in WinCC:

Execute OS Compilation with SFC Visualization:
* In SIMATIC Manager, right-click the OS project and select Compile.
* In the Select the data you want to compile dialog:
- Check Tags and messages.
- Check SFC Visualization.
- Check With interconnected partner (SFC option).
- Scope: Changes only (or Entire OS if compiling for the first time).
Instantiate Standard SFC Block Icon in Graphics Designer:
* Open the target process screen in Graphics Designer.
* From the @PCS7Typicals.pdl (or @PCS7TypicalsAPL.pdl) library, copy the standard SFC block icon (@SFC_TYPE/1 or @SFC_RTS/1).
* Paste the icon into the screen.
* Under Properties > General, set the property tag to the full technological path of the SFC Chart (e.g., Plant/Unit1/SFC_Reactor1).
* Save the picture.

Verification

Verify operating mode and state tracking in WinCC Runtime:
1. Activate WinCC Runtime.
2. Open the process screen: Confirm that the SFC block icon displays the current mode (e.g., solid green AUT).
3. Click the block icon to open the standard SFC faceplate (@pg_@sfc_rt.pdl).
4. Switch operating mode from Automatic to Manual: Confirm that the mode indicator on the overview screen immediately changes to MAN.
5. Start the sequence: Confirm that the state display advances from Ready to Running, and the active step name updates dynamically.

Limitations and Operational Precautions

Never attempt to edit the C-scripts inside @pg_@sfc_rt.pdl directly; any manual modifications will be overwritten when running the OS-Project Editor.
If an SFC Chart is renamed in SIMATIC Manager, an OS compile is mandatory to purge old WinCC tags and generate the new @<NewName> tag prefix.
When using SIMATIC BATCH, manual switching between AUT and MAN must be restricted via block input ENMAN = 0 while a batch is actively occupying the unit.

Engineer FAQ

Why didn't my new SFC Chart create any tags in WinCC after compiling the OS?

The most common cause is that the 'SFC Visualization' option was unchecked during the OS compilation wizard, or the SFC Chart was located in the Component View rather than an OS-assigned Plant Hierarchy folder.

Can I display the SFC state using a standard text list instead of the SFC block icon?

Yes. You can link a WinCC Text List object to the tag '@#status' and map the integer values to custom text strings (e.g., 2 = 'Running', 3 = 'Holding').

What is the difference in visualization between an SFC Chart and an SFC Type?

An SFC Chart compiles via system block FB300 with fixed tag suffixes. An SFC Type compiles as an instance FB with customizable interface parameters (such as QSTEP) that can have custom S7_m_c attributes.