Managing CFC Runtime Group Naming Conventions and Cleanup After Chart Replication in PCS 7

SIMATIC PCS 7 does not provide a native one-click automatic command to rename existing runtime groups (Ablaufgruppen) to match renamed CFC charts after copying. When charts are replicated within a project, CFC appends numerical suffixes (e.g., Chart_1) to preserve uniqueness. To synchronize runtime group names cleanly without manual editing, employ one of two established workflows: (1) Copy the newly created CFC charts into a temporary empty project where runtime groups generate matching names, delete old charts in the source project, run 'Delete Empty Runtime Groups', and copy back; or (2) Utilize Control Module Technology (CMT) or the Import/Export Assistant (IEA), which automatically name runtime groups according to the technological plant hierarchy tag.

Executive Summary

During mass engineering and replication of equipment logic in SIMATIC PCS 7 V9.0 SP2, automation engineers often duplicate existing CFC charts to create new process tags. However, copying charts generates runtime groups with appended suffixes (such as Motor_1, Motor_2) or retains stale names from the source chart. Manually expanding the Run Sequence editor (Ctrl+F11) and editing dozens of runtime group properties is tedious and prone to transcription errors. Because CFC lacks an automated 'Synchronize Runtime Group Names to Chart Names' menu command, engineers must understand the runtime group creation engine, employ project isolation workarounds, or leverage technological engineering tools like CMT to maintain clean controller execution structures.

Architecture and Fundamental Mechanics

The lifecycle and naming mechanics of runtime groups within the CFC environment are governed by specific structural rules:

Runtime Group Architecture: In PCS 7, Organization Blocks (such as OB1 or OB35) do not execute blocks directly. Instead, they execute Runtime Groups (Ablaufgruppen), which contain ordered collections of block calls. Each runtime group possesses attributes including Name, Comment, Reduction Ratio, Phase Offset, and Active status.
Automatic Generation on Chart Creation: When a new CFC chart is created from scratch, CFC automatically creates a runtime group in the default cyclic interrupt OB (typically OB35) matching the exact name of the chart (e.g., chart PMP_101 generates runtime group PMP_101).
Chart Replication Behavior: When an existing chart is copied within the same AS program, CFC detects name collisions in the runtime sequence. To avoid overwriting existing runtime groups, CFC appends a suffix (e.g., PMP_101_1). If the chart is subsequently renamed in the Plant Hierarchy to PMP_102, CFC renames the chart but leaves the runtime group name unchanged as PMP_101_1. This decoupling exists because a single chart may contain multiple runtime groups distributed across different OBs, making automated renaming ambiguous.
Technological Naming via CMT/IEA: Unlike raw chart copying, instantiating charts via Control Module Technology (CMT) or the Import/Export Assistant (IEA) utilizes the technological tag name defined in the Plant Hierarchy, dynamically generating matching runtime groups without legacy suffix artifacts.

Step-by-Step Implementation Procedure

To resolve mismatched runtime group names across replicated charts, utilize the following engineering procedures:

Method 1: The Temporary Project Re-import Workflow (Bulk Renaming)

In SIMATIC Manager, create a new, temporary empty STEP 7 project (File -> New).
In the source project, select all newly copied and renamed CFC charts.
Copy the charts and paste them into the chart folder of the temporary project. (Because the temporary project contains no conflicting runtime groups, CFC initializes runtime groups matching the new chart names).
In the original source project, delete the replicated charts that had mismatched runtime groups.
Open the CFC Run Sequence editor (Ctrl+F11) in the source project. Select Options -> Delete Empty Runtime Groups (Ablaufgruppen -> Leere Ablaufgruppen löschen) to purge orphaned runtime groups.
Copy the charts from the temporary project back into the source project Plant Hierarchy.

Method 2: Manual Renaming via Run Sequence Editor

Open any CFC chart in the AS program.
Press Ctrl+F11 (or select Edit -> Open Run Sequence).
Expand the target OB (e.g., OB35).
Right-click the mismatched runtime group, select Object Properties, and update the Name field to match the chart tag.

Method 3: Standardization Using Control Module Technology (CMT)

Cease direct CFC chart copying. Instead, define standard equipment types as CMTs in the Master Data Library.
Instantiate CMTs into the Plant Hierarchy. CMT automatically derives runtime group names directly from the technological tag.

Verification

Verify the alignment of runtime group names with CFC charts:

Run Sequence Inspection: Open the Run Sequence editor (Ctrl+F11). Expand OB35 (or the applicable OB). Scroll through the list of runtime groups and verify that every group name matches its corresponding CFC chart name.
Empty Group Check: Select Options -> Delete Empty Runtime Groups. Confirm that zero orphaned groups remain.
Compilation Check: Perform a CFC compilation (Changes Only). Verify that compilation completes with zero warnings regarding missing or duplicate runtime sequence positions.

Limitations and Operational Precautions

When performing the temporary project copy workflow, ensure that cross-chart interconnections outside the copied batch are not severed. Always archive the multi-project prior to deleting charts. Furthermore, never delete system runtime groups (OB1_START, OB1_END, @...) generated by CEMAT, Advanced Process Library, or module driver generators.

Engineer FAQ

Why does CFC not rename runtime groups automatically when a chart is renamed?

A single CFC chart can contain blocks assigned to multiple runtime groups across different OBs (e.g., OB1, OB35, OB86). Because a one-to-one mapping cannot be guaranteed for complex charts, CFC maintains independent chart and group names.

What does 'Delete Empty Runtime Groups' do?

It automatically removes any runtime groups that contain zero block calls, which often linger after blocks or charts are deleted.

Can runtime group names affect PLC execution or memory?

No. Runtime group names are purely symbolic references used for engineering organization; they do not alter CPU execution speed or load memory allocation.