Managing Control Module Types (CMT) and Type-Instance Synchronization in PCS 7

In SIMATIC PCS 7 (introduced in V8.0 and enhanced in V8.1/V8.2), Control Module Types (CMT) in the Master Data Library define standardized, object-oriented templates for process equipment (motors, valves, analog loops). When an engineer modifies a CMT in the library—such as adding an optional interlock or modifying parameters—the changes do not update instantiated Control Modules (CMs) automatically. Synchronization requires executing 'Options -> Plant Types -> Synchronize...' in SIMATIC Manager or using Process Automation Accelerator (PAA / AdvES) to propagate type modifications safely without overwriting instance-specific hardware addresses.

The Paradigm Shift: Process Tag Types vs. Control Module Types (CMT)

In legacy SIMATIC PCS 7 versions (V6.x and V7.x), mass engineering of repetitive process devices relied on Process Tag Types (PTT) and Import/Export Assistants (IEA). While functional, PTT had severe limitations: once a process tag was instantiated into a CFC chart, the architectural link between the template and the instance was largely severed. Modifying a template required complex re-import workflows that risked overwriting custom field tuning parameters.

Starting in PCS 7 V8.0, Siemens introduced Control Module Types (CMT):
* CMTs establish a true object-oriented type-instance relationship.
* An instantiated Control Module (CM) retains a permanent, persistent pointer to its master template in the Master Data Library.
* When the central CMT is modified in the library, the system provides automated synchronization tools to propagate structural changes across hundreds of plant instances in minutes, while rigorously preserving instance-specific attributes (such as I/O signal addresses, setpoints, and tag comments).

The Internal Structure of Control Module Types in the Master Data Library

A Control Module Type resides within the Master Data Library under the Plant Types folder. It comprises:
1. Technological Blocks: Core algorithm blocks (e.g. MotL, Pcs7DiIn, Pcs7DiOu).
2. Control Module Attributes: High-level technological definitions:
- Signals: Inputs and outputs mapped to field I/O (e.g. FbkRun, CommandOpen).
- Parameters: Setpoints, filter times, and mode selections exposed for mass engineering.
- Messages: Pre-configured alarm priorities and message texts.
3. Optional Elements (Variants): Blocks or interconnections that are conditionally enabled on specific field instances (e.g. an optional localized emergency stop button or optional current transmitter).

Handling Optional Variants and Sub-Control Modules

A breakthrough feature of CMT is the ability to define Optional Blocks:
* In older systems, if 80 motors were standard and 20 motors had vibration monitors, engineers were forced to create two separate templates (Motor_Std and Motor_Vib).
* With CMT, an engineer creates a single Motor_CMT containing the vibration monitoring block marked as an Optional Element.
* When instantiating the CMs, the engineer checks or unchecks the optional vibration block per instance.
* During synchronization, the type-synchronization engine updates the core motor logic across all 100 instances without removing or breaking the optional vibration blocks on the specialized units.

Process Tag Type vs. Control Module Type Comparison Matrix

The following matrix compares classic Process Tag Types with modern Control Module Types:

Engineering MetricClassic Process Tag Type (PTT)Modern Control Module Type (CMT)Underlying ConceptModel chart copy/paste templateObject-oriented Type-Instance modelType-Instance LinkLoose / Lost after instantiationPermanent, persistent database linkHandling VariantsRequires separate templates for each variantSingle CMT with Optional ElementsMass Parameter ChangesRequires IEA CSV export/importProcess Object View / PAA SynchronizationStructural UpgradesExtremely difficult (Risk of data loss)Automated Central SynchronizationAdvES / PAA IntegrationBasic tabular exchangeBidirectional CAE synchronization

Step-by-Step Procedure to Modify and Synchronize CMTs

To modify a master CMT and propagate changes across all plant instances:
1. Open the Master Data Library:
- In SIMATIC Manager, navigate to the Master Data Library.
- Expand the Plant Types folder.
- Open the target Control Module Type (e.g. CMT_Valve_Modulating).
2. Apply Structural Modifications:
- In the CFC editor, add the new block (e.g. insert an interlock block Intlk04 or an analog alarm block).
- Establish internal interconnections between the new block and existing blocks.
- Open the Technological Editor window: Define the new block's relevant parameters and signals as CMT attributes.
- If the block is optional, right-click the block in the Technological Editor and select Set as Optional.
- Save and close the CMT.
3. Initiate Type Synchronization:
- In SIMATIC Manager, select the Master Data Library container.
- Select Options -> Plant Types -> Synchronize....
- The Synchronization Wizard scans the Multiproject, listing all target AS projects and all instantiated CMs.
4. Review Differences in Comparison View:
- The wizard presents a detailed graphical difference tree showing exactly what will be added, modified, or preserved in each CM instance.
- Confirm that instance-specific I/O addresses and tag names are flagged as preserved.
5. Execute Synchronization:
- Click Synchronize. The wizard updates all instantiated CFC charts across the Multiproject.
- Execute a CFC compile (Scope: Changes only) and download changes in RUN to the controller.

Verification

Verify successful type-instance synchronization:
1. Open an instantiated Control Module chart (e.g. Valv_101) in an AS project.
2. Verify that the newly added block (e.g. Intlk04) appears in the chart with correct internal wiring.
3. Verify that existing field I/O connections (e.g. IW 512 position feedback) remain 100% intact and undisturbed.
4. In Process Object View (Ctrl + 4), select the Control Modules tab: Confirm that all instances report synchronization status: Up to date.

Limitations and Operational Precautions

Deleting a block from a master CMT will delete that block from all instantiated CMs during synchronization; ensure no critical custom field connections exist on blocks targeted for deletion.
Type synchronization must be executed on the Engineering Station; never attempt to synchronize types across a distributed team without checking out charts in multi-user engineering.
After synchronizing CMTs that alter block counts, perform an AS compilation (Changes only) to regenerate execution blocks.

Engineer FAQ

Can I modify an instantiated Control Module independently from its master CMT?

Yes. An engineer can add instance-specific logic to a CM chart. During synchronization, the wizard preserves custom logic provided it does not clash with the master CMT structure.

What is Plant Automation Accelerator (PAA)?

SIMATIC PCS 7 Plant Automation Accelerator (PAA) is an integrated engineering software tool bridging electrical CAE, P&ID instrumentation data, and PCS 7 CMTs, enabling bidirectional zero-loss engineering data exchange.

Does synchronizing CMTs require taking the controller to STOP?

No. In almost all cases, changes made via CMT synchronization can be compiled with 'Changes only' and downloaded to the S7-400 / CPU 410 controller in RUN mode.