Resolving Control Module Type (CMT) Synchronization Failures During PCS 7 V8 to V9.0 SP2 Migrations

In SIMATIC PCS 7, failures when synchronizing Control Module Types (CMT) during project migration from V8.x to V9.0 SP2 occur when block types in project charts have not been updated to match the upgraded library, or when instances contain structural divergences (such as manually deleted non-optional blocks or altered technological connections). To resolve synchronization failures, first execute 'Update Block Types' from the Master Data Library across all project charts, run 'Options -> Check Control Module Types' in SIMATIC Manager to identify specific instance divergences, correct non-optional block mismatches, and run 'Synchronize all instances' from the Plant Types menu.

Executive Summary

During plant modernization from SIMATIC PCS 7 V8.1/V8.2 to V9.0 SP2, engineering teams update master Control Module Types (CMTs) in the Master Data Library (e.g., incorporating updated APL V9.0 SP2 blocks, new interlock structures, or revised signal assignments). When attempting to propagate these changes across project charts using the 'Synchronize' command, the synchronization wizard frequently aborts or flags dozens of instances with errors like 'Cannot synchronize instance: Structural mismatch' or 'Block type version mismatch'. This guide explains the internal synchronization rules of the PCS 7 Plant Types engine, details root causes of instance divergences, and outlines the step-by-step remediation procedure.

Architecture and Fundamental Mechanics

The PCS 7 Control Module Type (CMT) synchronization engine enforces strict structural and cryptographic type-instance rules:
1. The Type-Instance Relationship in CMTs:
A CMT defined in the Master Data Library is a technological template. When instantiated as a Control Module Instance (CMI), the CFC chart maintains a cryptographic type reference pointer. The instance allows configuring unique parameters (e.g., setpoints, I/O addresses, comments) and toggling pre-declared optional blocks (variants). However, modifying the underlying block topology outside of variant rules breaks the type relationship.
2. Root Cause A: Block Type Version Mismatches:
When a project is migrated to V9.0 SP2, the Master Data Library is updated with APL 9.0 SP2 block types (e.g., MotL FB1850 with new feature bits). If an engineer modifies a CMT that contains the new block type, but the project charts still host older V8.x block types, the synchronization engine halts. Block types must be updated across all project charts before CMT synchronization is attempted.
3. Root Cause B: Unmanaged Instance Deletions / Additions:
If commissioning personnel previously opened an instance chart and manually deleted a standard block (instead of declaring it as an optional variant in the CMT), or manually added foreign blocks into the technological hierarchy, the synchronization engine detects a structural collision and refuses to synchronize to prevent overwriting unmanaged code.

Step-by-Step Implementation Procedure

Update Block Types in Project Charts First:
a. In SIMATIC Manager, open the Master Data Library.
b. Select the 'Blocks' folder.
c. Select Options -> Charts -> Update Block Types....
d. Select all project S7 programs and execute the update.
e. This ensures that block types (such as MotL, VlvL, MonAnL) in project charts match the exact versions in the master library.
Execute Pre-Synchronization Consistency Check:
a. In SIMATIC Manager, select the project root.
b. Select Options -> Check Control Module Types.
c. Review the generated log: identify specific error codes:
- 'Block missing in instance'
- 'Attribute mismatch on technological connector'
- 'Conflicting variant configuration'
  d. Open the faulted instance charts and review flagged blocks.
Correct Structural Inconsistencies in the Master CMT:
a. In the Master Data Library, open the CMT in the CFC Editor.
b. If certain plant instances do not require a specific block (e.g., an optional electrical trip feedback or auxiliary interlock), do not delete it from instance charts.
c. Instead, right-click the block in the CMT technological editor and configure it as an 'Optional' variant.
d. This permits instances to activate or deactivate the variant without breaking type conformity.
Execute Synchronize All Instances:
a. In the Master Data Library, select the Plant Types folder.
b. Right-click the modified CMT and select Plant Types -> Synchronize....
c. In the synchronization dialog, select 'Synchronize all instances' and click 'Check'.
d. Confirm that all instances display green checkmarks ('Ready to synchronize').
e. Click 'Synchronize' to execute the update across all charts.
Compile AS Charts with Delta Download:
a. In SIMATIC Manager, select the Charts folder -> Compile -> Changes only.
b. Download changes to the AS controller.

Verification

In SIMATIC Manager, re-run Options -> Check Control Module Types: verify 0 Errors, 0 Warnings across all project charts.
Open an updated instance chart: verify that new parameters, feature bits, and updated block interfaces reflect the master CMT changes while retaining unique field I/O connections.
Execute an online test in CFC: confirm that technological blocks monitor and control field actuators normally.

Limitations and Operational Precautions

Never force synchronization by deleting the instance and re-instantiating without backing up parameters; re-instantiating erases all customized instance setpoints, interlock linkages, and OS message comments.

Engineer FAQ

Why does CMT synchronization fail after migrating to PCS 7 V9.0 SP2?

Because the block types in project charts still hold older V8.x versions while the master CMT was updated with V9.0 SP2 blocks, or because instances have structural block divergences.

What must be done before synchronizing CMTs in a migrated project?

You must execute 'Update Block Types' from the Master Data Library to ensure all project charts share identical block versions with the library.

How do I handle blocks that are only needed on some motor instances?

Configure the blocks as 'Optional' variants inside the master CMT technological editor, rather than manually deleting them from instance charts.

Where can I find the exact reason an instance failed to synchronize?

Run the 'Options -> Check Control Module Types' command in SIMATIC Manager and inspect the generated diagnostic log.

Does CMT synchronization overwrite unique field I/O connections?

No. The synchronization engine is designed to preserve instance-specific parameters, signal connections, and comments while updating the master type structure.