Resolving CFC Error 1739:60451 'Illegal Parameter Assignment' When Copying Charts and Templates

In SIMATIC PCS 7, the compilation and copy error 'insert CFC (1739:60451) Illegal parameter assignment' occurs when copying a CFC chart, Process Tag Type (PTT), or template from a library into the Master Data Library or user project chart folder. This failure is caused by an internal block type collision: the destination S7 program contains an outdated or conflicting block type definition whose parameter signatures (data type, parameter length, or attribute mask) mismatch the incoming chart's blocks. To resolve the error, open the CFC Editor in the destination project, select 'Options > Block Types', click the 'Clean Up' button to remove all unused block types, and paste the chart again.

Executive Summary

Modular engineering in SIMATIC PCS 7 relies heavily on standardizing control logic through Process Tag Types (PTT) and template charts stored in the Master Data Library. When copying standardized charts (e.g. motor feeders, analog monitoring loops, or dosing templates) from an external library into an active project S7 Program, the paste operation frequently halts with the modal error insert CFC (1739:60451) Illegal parameter assignment. The destination folder refuses to accept the copied chart, halting template deployment. This error indicates that the destination S7 program database has cached an incompatible block version with mismatched parameter interfaces. This article explains the block caching architecture in CFC and details the clean-up procedure.

Architecture and Fundamental Mechanics

CFC Block Type Cache Architecture, Parameter Interface Signatures, and Database Collision Mechanics:

Architecture of the S7 Program Block Type Pool:
Within every S7 Program, the CFC Editor maintains an internal dictionary of Block Types (Options > Block Types).
When a function block (e.g. MotL, FB1850) is placed into any CFC chart, its interface definition (FB declaration table, input/output pins, default values, and data types) is registered permanently in the S7 program database.
The Mechanism of Error 1739:60451:
Over time, libraries are updated (e.g. from APL V8.1 to APL V9.0), or engineers modify custom blocks, adding or changing parameter types.
If the destination project once contained an older revision of a block type, that block's parameter signature remains cached in the S7 program database even if no active charts currently use it.
When the engineer copies a newer PTT template or CFC chart into the folder, the CFC insertion engine attempts to reconcile the incoming block's parameter list against the cached type definition.
If a parameter name now carries a different data type (e.g. INT changed to DINT, or an ANY pointer was modified), the compiler flags an Illegal Parameter Assignment (1739:60451) and aborts the insert operation to prevent database corruption.
The Role of Block Type Clean Up (Bereinigen):
The Clean Up function scans the entire S7 program, identifies all block types registered in the database that are NOT actively instantiated in any CFC chart, and purges their metadata records.
Once purged, the destination program has no conflicting cached signature, allowing the incoming chart to import its block types cleanly.

Step-by-Step Implementation Procedure

Open the CFC Editor in the Destination Project:
* In SIMATIC Manager, navigate to the target user project or Master Data Library.
* Open any existing CFC chart (or create a temporary blank chart and open it) to launch the CFC Editor.
Access the Block Types Management Dialog:
* In the CFC Editor menu, select Options > Block Types.
* In the dialog, examine the right-hand pane (Chart Folder), which lists all block types currently registered in the project.
Execute Block Type Clean Up:
* Click the Clean Up (Bereinigen) button located between the panes.
* A dialog appears listing all block types in the chart folder that are not currently used in any active CFC chart.
* Click Select All, then click OK (or Clean Up).
* Confirm that all unused cached block types are purged from the destination database.
Update Block Versions from Master Data Library (If Applicable):
* If the block is actively used by other charts, select the block type in the left pane (Master Data Library) and click New Version to update all existing instances to the current signature.
Re-copy the Chart or PTT Template:
* Return to SIMATIC Manager.
* Copy the desired CFC chart or PTT template from the source library.
* Paste it into the destination chart folder.
* Confirm that the paste operation completes instantly without Error 1739:60451.

Verification

Open the newly pasted CFC chart in the CFC Editor.
Confirm that all block pins, parameter connections, and sheet bar references render with normal colors and zero broken links.
Select Chart > Compile > Changes only; confirm that compilation succeeds with zero error dialogs.

Limitations and Operational Precautions

If a conflicting block type is actively used in dozens of existing charts, the 'Clean Up' dialog cannot remove it. In that case, you must use 'Options > Block Types > New Version' to upgrade all existing instances across the project to the new signature before pasting the template.

Engineer FAQ

What causes CFC error 1739:60451 'Illegal parameter assignment'?

A parameter signature mismatch between an incoming block type on the copied chart and an outdated cached block type in the destination S7 program.

How do I fix error 1739:60451?

In the CFC Editor, select 'Options > Block Types', click 'Clean Up', select all unused blocks, and clean them out before pasting.

Will 'Clean Up' delete blocks currently used in my charts?

No. The Clean Up function only removes block type definitions that have zero active instances in your project charts.

What is the difference between Clean Up and New Version?

'Clean Up' deletes unused block types from the project dictionary; 'New Version' updates existing active block instances to match an updated library block.