Understanding Model and Replica Plant Hierarchy Folder Icons in SIMATIC PCS 7

In SIMATIC PCS 7, an unfamiliar plant hierarchy folder icon displaying a dual-page or linked symbol represents a 'Replica' (an instantiated technological unit or equipment module), which is derived from a master 'Model' folder. Models are standardized, reusable technological templates—containing CFC charts, SFCs, OS graphics, and documentation—defined in the project or Master Data Library. Replicas are generated across plant units using the Import/Export Assistant (IEA). Changes made to the master Model can be updated and synchronized across all associated Replicas using IEA import files, ensuring modular consistency across identical process units.

Executive Summary

Managing large-scale chemical, pharmaceutical, or water treatment facilities often involves dozens of identical process units (such as bioreactors, filtration skids, or storage tanks). To eliminate repetitive manual programming, SIMATIC PCS 7 incorporates the Model and Replica engineering paradigm within the Plant Hierarchy (PH). When exploring inherited or migrated projects, engineers frequently encounter distinctively decorated folder icons that differ from standard yellow plant hierarchy folders. This visual distinction denotes a Replica folder tied to a master Model. This article explains the technical mechanics of Models and Replicas, details their integration with the Import/Export Assistant (IEA), and presents lifecycle synchronization best practices.

Architecture and Fundamental Mechanics

Plant Hierarchy Technological Classification, Model-Replica Architecture, and IEA Data Flow:

Standard Hierarchy Folders vs. Models and Replicas:
Standard Folder (Yellow Folder with Plant Symbol): A conventional organizational node in Plant View representing an Enterprise, Site, Area, or Unit under the ISA-88 / ISA-106 hierarchy.
Model (Muster - Blue Folder Icon with Template Glyph): A prototype folder designated as a technological master. It encapsulates all engineering artifacts required for a standardized equipment group: CFC control logic, SFC state machines, WinCC picture templates (.pdl), OS reports, and engineering documentation.
Replica (Replikat - Folder with Copy/Link Glyph): An instance generated from a Model. While each Replica contains concrete process variable assignments, signal addresses, and plant identifiers, it maintains an architectural reference to its parent Model.
The Import/Export Assistant (IEA) Coordination Engine:
Replicas are created and parameterized using the Import/Export Assistant (IEA).
The engineer exports the Model's parameters into an Import/Export File (CSV/text format).
In spreadsheet software, parameter tables are populated with instance-specific tags, hardware addresses, and message texts for Units 1 through N.
When IEA imports the file, it automatically creates the Replica folders, instantiates CFC/SFC charts, applies address connections, and assigns the distinctive Replica folder icon.
Type-Instance Synchronization and Modern Evolution:
If the master Model logic is modified (e.g. adding an interlock), re-running IEA synchronization updates all Replica folders without requiring manual chart rebuilding.
In PCS 7 V8.1 and higher, Models and Replicas represent the classical precursor to modern Control Module Types (CMT) and Equipment Module Types (EMT), but remain fully supported for legacy and hybrid project architectures.

Step-by-Step Implementation Procedure

Identify Model and Replica Designations in SIMATIC Manager:
* In SIMATIC Manager Plant View, right-click the folder displaying the special icon and select Object Properties.
* Select the Model/Replica tab.
* Check whether the radio button is set to Model, Replica, or Neutral.
* If it is a Replica, observe the field showing the path to the assigned parent Model.
How to Create a Master Model Folder:
* Create a standard Plant Hierarchy folder under your Master Data Library or project.
* Populate the folder with standard CFC charts (e.g. agitator, inlet valve, level sensor) and SFC types.
* Right-click the folder, open Properties, navigate to the Model/Replica tab, and select Model.
Generate Replicas Using the Import/Export Assistant (IEA):
* Right-click the Model folder and select Import/Export Assistant > Export.
* Select the parameters, I/O signals, and block comments to expose.
* Save the generated IEA file (e.g. Tank_Model.txt).
* Open the file in Excel; duplicate rows for each planned plant unit (e.g. Tank_01, Tank_02) and configure unique tag names.
* In SIMATIC Manager, select the plant destination folder, right-click, and select Import/Export Assistant > Import.
* IEA automatically generates the Replica folders with their distinctive icons and populated charts.
Synchronize Modifications from Model to Replicas:
* When engineering requirements change, edit the CFC logic inside the master Model folder.
* Re-export the IEA template and execute an IEA Update/Import on the Replica folders to propagate logic updates seamlessly.

Verification

Inspect Plant View; confirm that Model folders display the template glyph and Replica folders display the linked replica icon.
Open a chart inside a Replica folder; confirm that block interconnections and I/O addresses reflect the unit-specific IEA import data.
Perform an OS Compilation; verify that Picture Tree Manager builds the operator navigation hierarchy using the Replica unit names.

Limitations and Operational Precautions

Manually deleting individual blocks inside a Replica folder breaks type synchronization with the master Model. If individual skids require permanently unique control logic, convert the Replica to a 'Neutral' folder via Object Properties before modifying.

Engineer FAQ

What does the folder icon with a dual-page or copy symbol mean?

It represents a 'Replica' hierarchy folder instantiated from a master 'Model' folder using the Import/Export Assistant.

Where is the Model/Replica status configured?

In SIMATIC Manager, right-click the folder, select Object Properties, and view the 'Model/Replica' tab.

What is the advantage of using Models and Replicas?

It allows rapid bulk generation of identical process units and centralized synchronization of logic updates via IEA.

What is the difference between Models/Replicas and CMTs?

Models and Replicas duplicate entire folders containing multiple charts and pictures; Control Module Types (CMT) operate at the individual chart level.