How to Monitor Live WinCC Internal Tag Values in Legacy PCS 7 V7.0 vs Modern Configuration Studio

In modern PCS 7 versions (V8.0 and higher), WinCC Configuration Studio allows engineers to monitor internal tag values live by simply right-clicking the column headers in Tag Management and enabling the 'Value' and 'Quality Code' columns. In legacy PCS 7 V7.0 SP2, classic WinCC Explorer does not feature Configuration Studio or an online monitoring column. To monitor internal tags live in PCS 7 V7.0, engineers must place a temporary I/O Field linked to the tag on a graphic screen, use the WinCC Tag Simulator tool, write a diagnostic trace script using APDIAG, or view the tag via the WinCC Scope / Channel Diagnosis utility.

Evolution of WinCC Tag Management: Classic Explorer vs Configuration Studio

In SIMATIC PCS 7 Operator Stations (OS), Internal Tags reside purely in WinCC memory without physical controller addresses. They serve critical roles: coordinating graphic navigation, tracking logged-in operator privileges, storing calculated report parameters, and managing redundancy states (@RedundancyState).

The engineering workflow for monitoring internal tag values live during runtime changed radically across PCS 7 generations:
* Modern PCS 7 (V8.0, V8.1, V8.2, V9.x): Siemens introduced the WinCC Configuration Studio, a tabular spreadsheet-style editor integrated into WinCC Explorer. Configuration Studio supports live online connection to runtime, displaying live tag values and quality codes directly in the editor grid.
* Legacy PCS 7 (V7.0, V7.1, V6.x): WinCC Explorer uses the classic tree-view Tag Management editor. This legacy interface is strictly an offline configuration tool; it does not feature Configuration Studio, live table refreshing, or an 'Unhide Value' column.

Monitoring Live Internal Tags in Modern PCS 7 (V8.x / V9.x)

In PCS 7 V8.0 and higher running on Windows 7 or Windows Server 2008 R2:

Open Tag Management:
* Open the OS project in WinCC Explorer.
* Double-click Tag Management to launch WinCC Configuration Studio.
Navigate to Internal Tags:
* In the navigation tree on the left, expand Internal tags.
* Select a tag group (or the root Internal tags node).
Unhide the Value Column:
* Right-click any column header (such as Name, Data type, or Length).
* Select Unhide > Value (and optionally Unhide > Quality Code).
* A new column named Value appears.
View Live Runtime Data:
* When WinCC Runtime is active on the station, the Value column updates dynamically, showing live numbers, strings, and boolean states in real time.

Techniques for Monitoring Internal Tags in Legacy PCS 7 V7.0

If maintaining or troubleshooting a legacy PCS 7 V7.0 SP2 plant running Windows XP or Server 2003, use these approved diagnostic alternatives:

Method 1: Temporary I/O Field in Graphics Designer:
1. Open any non-critical mimic display (or create a temporary test picture test.pdl) in Graphics Designer.
2. Drag an I/O Field from the Smart Objects palette onto the canvas.
3. In the Configuration Dialog, link the I/O Field to the internal tag. Set update cycle to 1 second or Upon Change.
4. Save the picture and open it in WinCC Runtime to observe or overwrite the tag value live.
Method 2: APDIAG Diagnostic Output:
1. In Graphics Designer, place a button with a short C-action:
c #include "apdefap.h" void OnClick(...) { long val = GetTagWord("MyInternalTag"); printf("Live Tag Value = %ld\r\n", val); }
2. Launch apdiag.exe (C:\Program Files\Siemens\WinCC\uTools\apdiag.exe).
3. Click the button in Runtime and view the live value printed directly in the APDIAG output window.

Using WinCC Tag Simulator and APDIAG for Tag Verification

For comprehensive tag diagnostics without modifying plant graphic pictures:

WinCC Tag Simulator:
Located under Start > SIMATIC > WinCC > Tools > WinCC Tag Simulator.
Launch the tool while WinCC Runtime is running.
Click Open Tag and browse the internal tag list.
The simulator displays the current live value and provides simulation modes (Sine, Ramp, Random, Increment) to test tag-dependent graphic dynamics.
WinCC Channel Diagnosis:
For communication tags and driver-linked internal variables, open Channel Diagnosis from the Windows Start menu to inspect channel status and telegram counters.

Comparison of WinCC Tag Monitoring Methods Across Versions

The table below compares the internal tag monitoring options available across SIMATIC PCS 7 versions.

Diagnostic MethodPCS 7 V7.0 / V7.1PCS 7 V8.x / V9.xRuntime Modification?Engineering OverheadConfiguration Studio GridNot AvailableNative Feature (Unhide > Value)Yes (Overwritable online)Zero (Built-in)Temporary I/O FieldFully SupportedSupportedYesLow (Requires graphic edit)WinCC Tag SimulatorFully SupportedSupportedYes (Force values)Low (External utility)APDIAG printf TraceFully SupportedSupportedNo (Read-only trace)Moderate (Script required)WinCC Cross-ReferenceStatic onlyStatic onlyNoZero (Reference check only)

Verification

To confirm that internal tag values are monitoring accurately:
1. In WinCC Configuration Studio (modern) or your temporary I/O field (legacy), observe the initial tag value.
2. Trigger the logic or faceplate action that writes to the internal tag.
3. Confirm that the displayed value updates instantly to reflect the commanded state.
4. If testing with the WinCC Tag Simulator, force an incrementing sequence and verify that dependent WinCC graphic objects animate synchronously.
5. In legacy systems, remove temporary diagnostic I/O fields before final project sign-off.

Limitations and Operational Precautions

Never write unverified test values to critical internal system tags (such as @RedundancyState or @RM_MASTER), as altering system tags can trigger unexpected server failovers.
Do not leave WinCC Tag Simulator running on production operator stations; active simulation overrides process data.
In redundant OS server pairs, internal tags without the @ prefix are local to each server by default unless explicitly configured as project-wide tags.
When requesting technical assistance on Siemens forums, always specify the exact installed PCS 7 version, service pack, and operating system release.

Engineer FAQ

Why did right-clicking column headers do nothing in PCS 7 V7.0 Tag Management?

WinCC Configuration Studio was only introduced in WinCC V7.2 and PCS 7 V8.0. In PCS 7 V7.0, Tag Management uses classic WinCC Explorer grids that do not support runtime data binding or column unhiding.

Can internal tags be logged in WinCC Tag Logging?

Yes. Internal tags can be added to Tag Logging archive cycles just like physical AS process tags, allowing historical trending and archival.

What is the difference between tags starting with '@' and regular internal tags?

Tags starting with an '@' symbol (e.g., @CurrentUser, @RedundantServerState) are system-reserved internal tags created automatically by WinCC. Regular internal tags are user-defined variables created by engineers.