Control Module Technology Getting Started: Migrating from Process Tag Types to CMTs with BPCM Library

To get started with Control Module Technology (CMT) in SIMATIC PCS 7, adopt the Basic Process Control Modules (BPCM) Library templates as reference standards and instantiate them within your project Master Data Library (MDL). Unlike legacy Process Tag Types (PTTs) which replicate rigid, unmodifiable charts, CMTs encapsulate technological blocks, signals, parameters, and messages into modular types. Using the Technological Editor, engineers assign I/O attributes that synchronize bidirectionally across all plant instances. Structural changes made in the Master Data Library CMT propagate automatically via the Synchronize Editor without overwriting instance-specific setpoints or equipment tag names.

Executive Summary

Historically, SIMATIC PCS 7 utilized Process Tag Types (PTTs) and import/export files (IEAs) to duplicate standardized equipment control schemes such as motors and valves. However, PTTs exhibited severe architectural limitations: post-commissioning modifications required tedious manual chart edits or disruptive re-instantiations that risked overwriting operational tuning parameters. Beginning with PCS 7 V8.1, Siemens established Control Module Technology (CMT) as the standard engineering methodology, supported by the Basic Process Control Modules (BPCM) Library. CMTs separate technological definitions (signals, parameters, interlocks) from physical instance data. By migrating to CMTs, engineering teams enable bulk editing in Process Object View, seamless integration with Plant Automation Accelerator (PAA) and COMOS, and centralized lifecycle maintenance across multi-unit industrial facilities.

Architecture and Fundamental Mechanics

Control Module Technology (CMT) introduces an object-oriented abstraction layer directly within the SIMATIC PCS 7 Plant Hierarchy:

Type-Instance Paradigm: A Control Module Type (CMT) resides exclusively in the Master Data Library (MDL) under Plant Types -> Control Module Types. When instantiated into a Plant Hierarchy folder, it creates a Control Module (CM). Unlike simple CFC chart copies, a CM retains an active technological link to its parent CMT.
Technological Editor & Technological I/Os: Inside the CFC editor, the Technological Editor pane exposes the internal block interface as abstract technological objects: Signals (analog/digital I/O), Parameters (setpoints, time delays, limits), and Messages. Only elements declared in the Technological I/Os are exposed for bulk engineering and external exchange.
Synchronization Engine: When an engineer adds an optional block (e.g., an extra interlock or run-time counter) to the CMT in the Master Data Library, the changes do not require deleting existing plant instances. Executing Plant Types -> Synchronize scans the AS project, compares instance schemas with the library type, and applies structural updates in place while preserving all calibrated field parameters, setpoints, and interconnection references.
Role of the BPCM Library: The Basic Process Control Modules (BPCM) Library is a pre-engineered reference catalog provided by Siemens containing fully configured CMTs (e.g., single-speed motors, reversing drives, modulating valves, PID controllers). The BPCM Library serves as the baseline from which templates are copied into the project Master Data Library and customized.

Step-by-Step Implementation Procedure

Implement a CMT-based engineering workflow following these precise engineering procedures:

Incorporate BPCM Library Templates into Master Data Library:
- In SIMATIC Manager, select File -> Open -> Libraries and open the BPCM_Library.
- Navigate to Templates -> Control Module Types.
- Copy the required CMT templates (e.g., BPCM_MotL, BPCM_VlvL, BPCM_PIDConL) and paste them into your project's Master Data Library under Plant Types -> Control Module Types.
Customize Technological Definitions in the Master Data Library:
- Open the copied CMT in the Master Data Library using the CFC Editor.
- Open the Technological Editor via View -> Technological Views or the toolbar icon.
- Review the Technological I/Os. Drag additional block inputs or outputs (e.g., Feature, Permit, RstOp) from CFC blocks into the Technological I/O tree to expose them for instance configuration.
Instantiate Control Modules in Plant Hierarchy:
- Switch to Plant View in SIMATIC Manager.
- Drag the customized CMT from the Master Data Library directly into the target Plant Hierarchy hierarchy folder (e.g., Unit_01/Reactions).
- Rename the created Control Module (e.g., XV_101) to match the piping and instrumentation diagram (P&ID) tag name.
Perform Bulk Engineering via Process Object View:
- In SIMATIC Manager, select View -> Process Object View.
- Select the Control Modules and Signals tabs.
- Bulk-assign symbolic hardware addresses (I/O addresses), alarm limits, and engineering units to all instantiated CMs without opening individual CFC charts.
Modify and Synchronize Types:
- When modifications are required later, open the CMT in the Master Data Library and apply the logic changes.
- Right-click the AS project in Plant View and select Plant Types -> Synchronize.
- Select the modified CMT and click Synchronize. Review the comparison log and confirm the non-destructive propagation.

Verification

Validate CMT integrity and synchronization across the automation system:

Instance Integrity Check: Open an instantiated CM chart. Verify that blocks display blue technological assignment badges in their headers indicating valid linkage to the Master Data Library.
Synchronization Verification: Add a test parameter to the CMT in the Master Data Library. Run Plant Types -> Synchronize. Inspect the target CM to confirm the new parameter appears with default values while existing I/O interconnections remain untouched.
Process Object View Consistency: In Process Object View, verify that the Control Module Types column correctly shows the library version and timestamp, with zero unassigned technological signals.

Limitations and Operational Precautions

CMTs must strictly reside in the project Master Data Library before instantiation; never drag CMTs directly from the external BPCM Library into plant folders, as direct links to read-only external libraries will break synchronization and variant editing. Furthermore, while CMT synchronization preserves instance parameters, deleting an interconnected block or signal inside a CMT will sever external interconnections on all plant instances upon synchronization. Always back up the Master Data Library prior to executing bulk synchronization.

Engineer FAQ

Can I convert existing legacy Process Tag Types (PTTs) into Control Module Types?

Yes. SIMATIC PCS 7 provides a conversion utility in SIMATIC Manager under Options -> Plant Types -> Migrate Process Tag Types. The tool inspects PTT charts and imports them into the Master Data Library as valid CMT structures.

Is the BPCM Library mandatory to use Control Module Technology?

No. The BPCM Library is an optional application library providing standardized starting templates. Engineers can create empty CFC charts, define Technological I/Os from scratch, and create completely proprietary CMTs in their Master Data Library.

What is the difference between CMT and EMT?

A Control Module Type (CMT) encapsulates single equipment units (motors, valves, transmitters). An Equipment Module Type (EMT) encapsulates multi-device technological units (dosing units, agitator trains) coordinating multiple CMTs and SFC phase sequences.

Why do instance parameter changes revert after synchronization?

Instance parameters only revert if they are marked as 'Type' attributes rather than 'Instance' attributes in the Technological Editor. Ensure parameters intended for field tuning are marked as 'Instance' specific in the CMT definition.

Does CMT synchronization require an AS controller stop?

No. Structural modifications to CMTs can be compiled and downloaded using CFC Changes-Only mode (Download in RUN), provided the controller has sufficient spare memory and block types are not being deleted.