Batch Editing Sequential Function Charts (SFC) and SFC Types: Tabular Modification and Migration Strategies in PCS 7

In SIMATIC PCS 7 V8.2, native Process Object View does not support tabular mass editing of step actions and transition conditions inside standalone SFC charts. When migrating projects from legacy libraries (like standard chemical blocks) to APL, engineers must convert standalone SFC charts into parameterized SFC Types. Inside an SFC Type, step actions and transitions are parameterized symbolically using setpoints and characteristics, which CAN be bulk-managed in tabular format via the Process Object View 'SFC' tab, or exported and modified using the Advanced Engineering Station (AdvES) / COMOS / XML interface to execute mass search-and-replace operations across hundreds of sequential steps.

Challenges of Mass Engineering in Sequential Control Systems

In continuous and batch process plants (chemical reactors, clean-in-place skids, packaging lines), sequential operations are implemented using Sequential Function Charts (SFC). A major engineering challenge arises when a plant executes a major library modernization—for example, migrating from classic PCS 7 Standard/Chemistry Library to the Advanced Process Library (APL).

In legacy libraries, valves were commanded via discrete parameters like AUT_ON or CMD_OPEN. In APL, drive blocks (VlvL, MotL) utilize structured control pins (e.g., ModLiOp, AutModLi, OpenAut). In projects containing dozens of SFCs with thousands of steps and transitions, manually opening every single step dialog to re-interconnect actuator commands is extraordinarily labor-intensive.

SFC Charts vs SFC Types: The Key to Tabular Parameterization

To understand the limitations and solutions, engineers must distinguish between the two SFC implementations in PCS 7:

Standalone SFC Charts: A standalone SFC is an individual drawing entity hardwired directly to specific CFC block pins. The internal step actions and transition boolean logic are embedded within the chart graphic. The PCS 7 Process Object View does not expose internal step actions of standalone SFC charts; they cannot be edited in tabular spreadsheets.
SFC Types (Type-Instance Concept): An SFC Type is a reusable class definition stored in the Master Data Library. Step actions and transitions reference abstract Control Strategies, Setpoints, and Characteristics. When an SFC Type is instantiated as an SFC Instance, all parameters, setpoints, and phase configurations are exposed as structured data. Crucially, SFC Type instances CAN be edited in tabular format in Process Object View under the 'SFC' tab.

Export/Import Capabilities: AdvES, CAx, and XML Engineering Interfaces

When mass modifications across step actions are mandatory, modern engineering environments provide programmatic pathways:

SIMATIC PCS 7 Advanced Engineering System (AdvES): AdvES provides a relational data layer above SIMATIC Manager. While primarily focused on CFC signals and hardware, AdvES can import and export equipment phase assignments and parameters via Microsoft Excel.
CAx Data Exchange / XML Export: PCS 7 supports the CAx interface (Options > CAx Data Exchange), which serializes charts, blocks, and connections into XML or ASCII files. Engineers can execute automated script search-and-replace routines (e.g., using Python or PowerShell) to transform legacy parameter names to APL pins, and re-import the file into the project.
CFC Connection Move Feature: In CFC, dragging a signal connection from an old block pin to a new block pin automatically moves all interconnected SFC step actions bound to that pin.

Step-by-Step Migration and Tabular Editing Workflow

Follow this sequence to modernize sequential logic efficiently:

Convert Standalone SFCs to SFC Types: For repetitive process equipment (e.g., reactor phases, filter washes), develop standardized SFC Types in the Master Data Library using APL block interfaces.
Instantiate SFC Types in Plant Hierarchy: Place SFC instances in the plant hierarchy folders matching the equipment units.
Open Process Object View: In SIMATIC Manager, select View > Process Object View. Navigate to the SFC tab.
Batch Parameterize Setpoints: In the tabular grid, configure setpoints, target values, and timing parameters. Copy/paste values across instances directly from Excel.
For Remaining Standalone SFCs: Open the SFC Editor. Use the Options > Chart Reference Data cross-reference list to locate all instances of legacy block parameters. Double-click entries to jump directly to the target step for updating.
Compile SFCs: Compile the SFC types and instances; verify zero syntax errors.

SFC Engineering Tool Capability Matrix

The following table compares different engineering tools and their capabilities for editing PCS 7 SFCs:

Engineering ToolStandalone SFC StepsSFC Type ParametersTabular Mass Editing?Search / Replace SupportStandard SFC EditorSupportedSupportedNO (Dialog-based per step)Basic text search within chartProcess Object View (POV)Not SupportedSupported (SFC Tab)YES (Spreadsheet grid)Full column filter and replaceAdvES (Advanced ES)LimitedSupportedYES (Excel round-trip)Bulk search/replace in ExcelCAx XML Data ExchangeSupported (XML)Supported (XML)Conditional (Via script)Global script search/replaceSIMATIC BATCH Recipe EditorN/A (Recipes only)Master RecipesYES (BatchCC grid)Recipe parameterization

Verification

Verify sequential logic integrity through the following steps:

In the SFC Editor, select Options > Check Consistency. Ensure that all transitions, step actions, and terminations pass validation.
Compile the AS program (Charts as Program > Entire Program with SFC compiler enabled). Confirm zero compile errors.
In S7-PLCSIM or online test mode, open the modernized SFC in test mode. Force start conditions and step through the sequence.
Confirm that new APL actuator blocks (VlvL, MotL) receive their start/stop commands in automatic mode and that feedback signals satisfy transition criteria without timing timeouts.

Limitations and Operational Precautions

Consider these operational rules when modernizing SFC logic:

Never Modify SFC Step Actions on an Active Batch: Downloading changes to an active SFC executing a live production batch can reset internal step timers, causing sequence halts or opening incorrect ingredient valves.
APL Command Holding Behavior: Standard APL blocks require continuous high signals on OpenAut / StartAut or pulse commands depending on Feature bit settings; ensure SFC step actions match the drive block's pulse/continuous parameterization.
SFC Delta Download Rules: Modifying step actions within existing steps is delta-downloadable in RUN, but adding or deleting steps and transitions requires compiling the entire SFC and may require sequence deactivation.

Engineer FAQ

Can CAx XML export be used to modify SFC charts?

Yes, by exporting the project using CAx Data Exchange, an engineer can process the resulting XML files programmatically to replace old block parameter names with new APL pins.