Cross-Referencing and Monitoring I/O Signals and Graphic Tag Connections in SIMATIC PCS 7 and WinCC

In SIMATIC PCS 7, engineers transitioning from third-party DCS/SCADA platforms can inspect and cross-reference all plant I/O signals simultaneously using the Process Object View (PO View) in SIMATIC Manager. PO View provides comprehensive, sortable tables for Signals, Parameters, Messages, and Archive Tags with live online monitoring capabilities. In WinCC, engineers can display all tags and scripts connected to a specific process picture using the 'Linking -> Tag Connections' dialog in Graphics Designer or by generating an automated object dependency report via the WinCC Cross-Reference utility.

Centralized I/O Management via the Process Object View

Engineers arriving at SIMATIC PCS 7 from platforms such as GE Fanuc, Rockwell PlantPAx, or Honeywell Experion often look for a central tag database editor to view all physical I/O points, channel assignments, and live values in a single tabular sheet.

In PCS 7, this central engineering nexus is the Process Object View (PO View) located within SIMATIC Manager (View -> Process Object View):
* Tabular Plant Overview: Aggregates all CFC charts, SFC sequencers, and I/O channels across the entire multiproject into a structured spreadsheet.
* The 'Signals' Tab: Lists every physical and logical input/output channel, including symbolic tag names, hardware addresses (e.g., IW 512), signal comments, engineering units, and channel driver blocks.
* Bulk Editing Capabilities: Allows engineers to reassign I/O addresses, modify scale limits, adjust alarm setpoints, and update comments globally without opening individual CFC charts.

Inspecting Live Controller I/O via VAT Tables and HW Config

To monitor live physical values directly on the controller during commissioning:

1. Hardware Configuration Monitor/Modify

In HW Config, right-click any digital or analog signal module (e.g., an SM 331 8xAI card) in an ET 200M rack and select Monitor/Modify.
A live table displays all channels on that specific card, showing raw HEX counts and integer values updated in real time.

2. Variable Tables (VAT)

In the S7 Program -> Blocks folder, insert a Variable Table (VAT).
Engineers can enter physical I/O addresses (IW 512, QW 256), memory bits (M), or data block parameters (DB10.DBD20).
Clicking the Monitor Variable (glasses) icon displays live decimal or floating-point values. Values can also be modified or forced directly from this view.

Comparison Table - PCS 7 Signal and Tag Inspection Tools

The following table details the primary tools available in PCS 7 for cross-referencing and inspecting controller signals and WinCC graphic tags.

Tool NameSoftware DomainPrimary PurposeLive Online Monitoring?Bulk Edit Support?Process Object View (PO View)SIMATIC ManagerMultiproject I/O, parameters, and message cross-referenceYes (via Test Mode)Yes (Full bulk editing)Variable Table (VAT)STEP 7 / CFCCommissioning and forcing specific physical addressesYes (Direct controller reads)Limited to forcingHW Config Monitor/ModifySTEP 7 HW ConfigTesting individual module channels on physical racksYes (Raw hardware levels)No (View/Modify only)Graphics Designer Tag LinkingWinCC GraphicsList and replace all tags connected to an active PDLNo (Offline engineering)Yes (Bulk tag find/replace)WinCC Cross-ReferenceWinCC ExplorerComplete audit report of all tags, pictures, and C/VBS scriptsNo (Audit tool)No (Read-only reports)WinCC Tag ManagementWinCC ExplorerLive monitoring of all WinCC runtime tagsYes (Shows live runtime values)Limited editing

Step-by-Step Procedure to Inspect Graphic Tag Connections in WinCC

To see every tag interconnected within a specific WinCC process picture (.pdl), execute the following workflow:

Inspect Tags via Graphics Designer 'Tag Connections':
* Open the target picture in WinCC Graphics Designer.
* In the top menu bar, select Edit -> Linking -> Tag Connections.
* A dialog opens listing every graphic object (buttons, analog displays, block icons) alongside its bound WinCC tag name.
* To re-route signals, select an existing tag and enter a replacement tag, or click Find and Replace to update tag prefixes globally.
Generate Comprehensive Cross-Reference Audit:
* Open WinCC Explorer.
* In the left project tree, double-click Cross-Reference.
* In the Cross-Reference assistant:
- Select Pictures as the search scope.
- Select the specific picture file (e.g., Reactor_Area.pdl).
- Check Used tags, Used pictures, and Used functions.
- Click Start. The tool generates a detailed cross-reference report displaying every tag, its data type, and the exact object property or script line where it is referenced.
Monitor Live Values in WinCC Tag Management:
* Activate WinCC Runtime.
* Open WinCC Explorer and expand Tag Management -> Named Connections -> [Your_AS].
* Select a tag group. The right-hand pane displays live columns for Value and Quality Code, updating dynamically from the controller.

Verification

Confirm that cross-referencing and signal monitoring tools operate correctly:

Verify Live Monitoring in PO View:
* In SIMATIC Manager, open Process Object View.
* Select the Parameters tab.
* Click the Test Mode (glasses) icon. Confirm that parameter values switch from static text to live green values updating from the AS.
Verify Tag Linking Accuracy in WinCC:
* In Graphics Designer, open Edit -> Linking -> Tag Connections.
* Click on any tag listed; confirm that the corresponding graphic element highlights on the canvas.
Verify Cross-Reference Export:
* In the WinCC Cross-Reference editor, click Export to save the tag list to CSV or Excel for documentation and verification.

Limitations and Operational Precautions

Avoid Forcing Values on Safety Signals: Never use Variable Tables (VAT) to force inputs or outputs connected to fail-safe blocks (F_CH_AI, F_CH_DI); forcing fail-safe channels can compromise functional safety.
Saving Variable Tables: Variable tables saved in the offline block folder should be kept clean of temporary force values before compiling or archiving projects.
Bulk Editing Precaution in PO View: Modifications made in Process Object View write directly into the underlying CFC charts; always perform a project backup before executing mass search-and-replace operations.

Engineer FAQ

Can Process Object View export all I/O signals to Microsoft Excel?

Yes. In PO View, selecting all rows (Ctrl+A) and copying (Ctrl+C) allows pasting directly into Excel. Furthermore, PO View supports direct export and import via CSV files.

Why are some tags missing from WinCC Cross-Reference?

Tags that are assembled dynamically inside C-scripts or VBScripts via string concatenation (e.g., strcat('Motor1', '.PV')) cannot be detected by static cross-reference parsers. Always declare tags symbolically or use standard APL tag prefixing.

What is the difference between PO View and the Symbol Table?

The Symbol Table lists only flat peripheral addresses and global DBs. PO View understands the full PCS 7 object hierarchy, displaying chart names, block types, interconnected technological pins, and WinCC message parameters.