Resolving IEA Error Cannot Create Hierarchy Folder During Bulk Model Import

The Import/Export Assistant (IEA) error 'Cannot create hierarchy folder...' occurs during bulk model import when the template folder in the Plant Hierarchy contains an conflicting or active OS assignment. When the source process tag type or model directory is explicitly linked to an Operator Station, the IEA fails to replicate nested hierarchy folders because target hierarchy levels cannot inherit or duplicate active OS compile assignments automatically. The standard solution removes the OS assignment from the source Models directory in the Plant View Object Properties before executing the IEA import. Once bulk generation concludes, target hierarchy folders can be assigned to the appropriate OS server.

Plant Hierarchy (PH) and Model Inheritance Rules

In SIMATIC PCS 7, the Import/Export Assistant (IEA) enables rapid bulk engineering of repetitive units (pumps, valves, analog loops) by instantiating Process Tag Types (PTT) and Models. A 'Model' is a structured hierarchy folder containing Continuous Function Charts (CFC), Sequential Function Charts (SFC), and nested folders.

The Plant Hierarchy assigns structural attributes to each folder—such as 'Higher Level Designation' (HID), 'AS Assignment', and 'OS Assignment'. When the IEA reads the import file (CSV/IEA format), it recursively builds the target directory structure. However, if the source template model folder contains conflicting system-level bindings, the hierarchy engine halts folder creation to prevent database corruption.

Root Cause of IEA Folder Creation Failures

The table below details hierarchy attribute conflicts and their diagnostic impact:

Hierarchy ParameterModel (Template) SettingTarget Project StateError Diagnostic ResultOS AssignmentLinked to specific OS (e.g., OS(1))Empty or different OS assignedError 'Cannot create hierarchy folder': IEA blocks folder creation due to conflicting OS assignment.AS AssignmentLinked to specific AS controllerTarget AS controller specified in IEA fileSuccessful creation; charts automatically assigned to specified target AS.Hierarchy DepthExceeds configured project level limitProject Plant Hierarchy max levels (e.g., 5 levels)Error 'Hierarchy level exceeded'; path truncated.

Remediation Workflow for Bulk Import

To resolve the error and successfully import multiple instances of a model:

Step 1: Remove OS Assignment from the Source Model Directory

In SIMATIC Manager, switch to Plant View.
Navigate to the folder containing your source Model / Process Tag Type.
Right-click the Model root folder and select Object Properties.
Select the Plant Hierarchy tab.
Locate the Assigned OS dropdown list and select (None) (leave blank).
Click OK to save the changes.

Step 2: Execute IEA Import

Open the IEA File Editor or select Options -> Plant Hierarchy -> Import....
Select the updated IEA import file containing your tag instances.
Execute the import: the IEA will create all target hierarchy folders, instantiate the CFC charts, and apply tag parameters without folder generation errors.

Step 3: Reassign Target Hierarchy Folders to the Destination OS

After the import completes, assign the newly created operational unit folders to the target OS Server project in their respective Object Properties.

Verification

To verify that the model import executed cleanly:

In SIMATIC Manager Plant View, expand the newly generated plant hierarchy branch.
Confirm that all nested folders and CFC charts appear with correct names and hierarchical pathing.
Open one of the newly instantiated CFC charts and verify that block parameters match the import table.
Right-click the top-level unit folder -> Plant Hierarchy -> verify that AS and OS assignments can now be applied without warnings.
Execute a consistency check (Plant Hierarchy -> Check Consistency) and verify zero errors.

Limitations and Operational Precautions

Operational boundaries when utilizing the Import/Export Assistant:

Plant Hierarchy Level Limits: Ensure the depth of the imported folder structure does not exceed the maximum number of hierarchy levels configured under Options -> Plant Hierarchy -> Customize.
Tag Name Length (HID): The total hierarchical path name plus chart name cannot exceed 128 characters (or configured Windows/WinCC limits).
CMT Transition: For modern PCS 7 V8.1/V9.0+ projects, Siemens recommends utilizing Control Module Types (CMT) and Technological IO over legacy IEA Models.

Engineer FAQ

Why does an OS assignment on a template model break IEA folder creation?

An OS assignment binds charts to a specific WinCC database. During automated folder duplication, the IEA cannot resolve whether to clone the OS target or overwrite existing OS links, triggering a folder creation abort.

Can IEA automatically assign target charts to different controllers?

Yes. In the IEA import table, you can explicitly define the destination AS controller name for each instantiated row.

What is the difference between a Process Tag Type (PTT) and a Model in IEA?

A Process Tag Type consists of a single CFC chart, whereas a Model consists of an entire plant hierarchy folder structure containing multiple CFCs, SFCs, and subfolders.

Does this error also affect Control Module Types (CMT)?

No. Control Module Types (CMT) in PCS 7 V8.1+ manage technological hierarchies independently of OS compile assignments, avoiding this legacy IEA limitation.