Architectural Constraints on Renaming Chart-in-Chart Objects and Parameter Visibility in Process Object View

In SIMATIC PCS 7, the inability to rename a nested 'Chart-in-Chart' object directly within the Process Object View (POV)—as well as the absence of Chart I/O pins in the POV Parameters tab—is a permanent architectural constraint of classic nested CFC charts. In PCS 7 data structures, a Chart-in-Chart is treated strictly as a graphical grouping container, not as a standardized technological process tag or function block. Consequently, the Process Object View does not expose Chart-in-Chart internal pins as addressable parameters. To rename a Chart-in-Chart, engineers must open the parent CFC chart, right-click the nested chart frame, and edit its properties directly. For modular logic requiring centralized renaming and mass parameterization in POV, Siemens mandates migrating nested charts to Control Module Types (CMT).

Executive Summary

During mass engineering and logic structuring in SIMATIC PCS 7, engineers frequently organize complex equipment logic using 'Chart-in-Chart' techniques—nesting subordinate CFC charts inside master parent charts. When attempting to perform mass renaming or parameter adjustments via the Process Object View (POV), engineers encounter a software roadblock: Chart-in-Chart names cannot be edited in the POV tables, and their input/output boundary parameters fail to appear under the Parameters tab. This technical guide explains the underlying data modeling differences between graphical Chart-in-Chart containers and technological Control Module Types (CMT), detailing the proper methods to manage existing nested charts and outlining the migration path to CMTs.

Architecture and Fundamental Mechanics

The data modeling architecture of SIMATIC PCS 7 differentiates graphical nesting from technological engineering:
1. The Chart-in-Chart Paradigm (Legacy Graphical Nesting):
- Introduced in early versions of CFC to segment visual clutter across large charts.
- A Chart-in-Chart is essentially a subordinate .cfc file referenced inside a parent .cfc canvas.
- Its interface pins ('Chart I/Os') are visual connection stubs rather than formal block parameters registered in the project's S7 block database.
2. Process Object View (POV) Architecture:
- The POV is an engineering database viewer built for Technological Engineering.
- It queries the database for:
a. Technological Blocks (FB instances with S7_m_c attributes).
b. Plant Hierarchy folders and Process Tags.
c. Control Module Types (CMT) and Control Modules (CM).
- Because a Chart-in-Chart is neither an FB instance nor a top-level Process Tag, the POV database parser skips its internal boundary parameters, and locks its name cell to prevent schema corruption.
3. The Modern Solution: Control Module Types (CMT):
- Modern PCS 7 engineering replaces nested Chart-in-Charts with Control Module Types (CMT) and Control Modules (CM).
- In CMT architecture, sub-functions (e.g., motor protection, interlock matrices) are modeled as optional sub-control modules. All parameters, signals, and messages are registered as technological attributes, providing 100% visibility, bulk editing, and renaming capabilities inside the Process Object View.

Step-by-Step Implementation Procedure

Rename a Chart-in-Chart Directly via CFC Editor:
a. Open SIMATIC Manager and locate the parent CFC chart in the Plant Hierarchy.
b. Double-click the parent chart to open it in the CFC Editor.
c. Locate the nested Chart-in-Chart block frame on the canvas.
d. Right-click the header of the nested chart and select Object Properties.
e. In the properties dialog, modify the Name field (e.g., change SubChart_01 to Dosing_Phase_Logic).
f. Click 'OK' and save the parent CFC chart.
Manage Chart I/O Pins in CFC Editor:
a. To edit, add, or reconnect boundary pins on a Chart-in-Chart:
- Open the parent chart in CFC Editor.
- In the main menu, select View -> Chart I/Os (or click the Chart I/Os icon).
- The Chart I/O interface bar expands at the top of the window.
- Rename pins or modify default values directly within this interface bar.
Modernizing to Control Module Types (CMT) for POV Integration:
a. Open the Multiproject's Master Data Library.
b. Create a new Control Module Type (CMT) in the CMT folder.
c. Insert the required APL technological blocks (MotL, VlvL, Intlk02) onto the CMT canvas.
d. Open the 'Technological Editor' tab in the left pane of CFC.
e. Drag and drop block parameters (e.g., AutModLi, SP_Ext) into the Technological Attributes list to expose them as formal CMT parameters.
Perform Mass Parameterization in Process Object View:
a. Return to SIMATIC Manager and select the top-level Plant Hierarchy folder.
b. Open the Process Object View (View -> Process Object View).
c. Navigate to the Parameters tab: observe that all parameters exposed via CMT now populate the table.
d. Filter, sort, and edit parameters in bulk, or export to Microsoft Excel for formula-based manipulation.

Verification

In CFC Editor, verify that the renamed Chart-in-Chart reflects the updated title on its canvas header.
In the Process Object View 'Process Tags' tab: confirm that newly instantiated Control Modules display full renaming and parameter editing capabilities.
Perform a delta compilation of AS charts: confirm compilation completes with 0 errors.

Limitations and Operational Precautions

Directly modifying compiled DB addresses or symbols of Chart-in-Chart elements bypassing the CFC editor will cause internal database corruption. Always perform structural edits inside the CFC editor.

Engineer FAQ

Why can't I rename a Chart-in-Chart in the Process Object View?

Because a Chart-in-Chart is treated as an internal graphical container rather than a technological process tag; its name can only be edited inside the parent CFC editor.

Why do Chart I/O parameters not appear in the POV Parameters tab?

The POV Parameters tab only lists parameters of technological function blocks; Chart-in-Chart boundary pins are not registered as technological block parameters.