Centralizing Bypassed Interlock Monitoring in Legacy PCS 7 V7.1 and CEMAT Applications

In legacy SIMATIC PCS 7 V7.1 and CEMAT environments, centralized monitoring of bypassed interlocks via an automated object browser was not natively supported, as full bypass visualization was introduced in PCS 7 V8.0 SP1. To implement centralized bypassed interlock monitoring in V7.1 without system upgrades, interconnect the BypAct (Bypass Active) output of all APL interlock blocks to an aggregated Data Block in CFC, configure the DB with Operator Control and Monitoring (S7_m_c = true), and display the aggregated status on custom WinCC overview faceplates.

Evolution of Interlock Bypass Architecture Across PCS 7 Releases

In heavy process industries such as cement, mining, and mineral processing running SIMATIC PCS 7 with CEMAT (Minerals & Cement Automation Library), equipment interlocks (lubrication pressure, bearing temperatures, chute blockage detectors) are critical for preventing catastrophic mechanical failures.

During maintenance or emergency startup, operators and maintenance engineers frequently require the ability to bypass an interlock temporarily. In modern PCS 7 versions (V8.0 SP1 through V9.x), the system includes native Bypass Management:
* Interlock blocks provide individual bypass switches (BypIn01 through BypIn16).
* When bypassed, an active bypass counter increments.
* An integrated Bypassed Interlocks Browser in WinCC provides an interactive list of every bypassed sensor across the entire plant.

In PCS 7 V7.1 (with WinCC V7.0 SPx and the early Advanced Process Library AdvLib71), the underlying blocks provided the signal output BypAct (Bypass Active), but the centralized WinCC Object Browser only tracked classic CEMAT overridden/simulated objects, completely ignoring APL interlock blocks. Maintenance teams were unable to quickly determine which safety interlocks were bypassed across the plant.

Bypass Monitoring Capabilities Across Software Generations Matrix

Compare native bypass tracking capabilities across PCS 7 and CEMAT releases:

System GenerationWinCC VersionNative Bypassed Interlock Browser?APL Interlock Block VersionCentralized Monitoring MethodPCS 7 V7.1 + CEMAT V7.1WinCC V7.0 SP3No (Supported only CEMAT simulation)AdvLib71 (FB1824-FB1827)Custom aggregated DB with S7_m_c + WinCC Pop-upPCS 7 V8.0 Base ReleaseWinCC V7.2Partial (Local faceplates only)APL V8.0Local icon indicators; manual script checksPCS 7 V8.0 SP1 / V8.1WinCC V7.2 / V7.3Yes (Official Bypassed Interlock List)APL V8.1Native BPC Bypassed Interlocks BrowserPCS 7 V8.2 / V9.x + CEMAT V8.xWinCC V7.4 / V7.5Yes (Full Plant Hierarchy Integration)APL V8.2 / V9.xUnified CEMAT / APL Object Browser

Safety engineering notice: Centralized bypass visibility is mandatory for plant safety management under IEC 61511.

Designing an Aggregated Bypass Monitoring Data Block in CFC

To centralize bypassed interlocks in PCS 7 V7.1 without a software upgrade:

Create an Aggregation Data Block in STEP 7:
* In the S7 program block folder, create a dedicated data block: DB500 (Symbolic Name: Bypass_Monitor).
* Declare arrays of binary flags or DWORD bitmasks representing each technological area:
scl DATA_BLOCK DB500 TITLE = 'Bypass Monitoring Aggregator' { S7_m_c := 'true' } STRUCT Kiln_Interlocks_Bypassed : DWORD; // Bitmask of Kiln interlocks Mill_Interlocks_Bypassed : DWORD; // Bitmask of Raw Mill interlocks Total_Bypassed_Count : INT; // Total active bypasses END_STRUCT; BEGIN END_DATA_BLOCK
Interconnect BypAct Signals in CFC:
* Open the technological CFC charts for the target plant area.
* On each Intlk02, Intlk04, Intlk08, or Intlk16 block, locate the output parameter BypAct (Bypass Active).
* Interconnect BypAct to the specific bit of DB500 representing that drive or gate.
Calculate Total Bypass Counter:
* In CFC, insert an adder block or counter to tally all active BypAct signals into DB500.Total_Bypassed_Count.

Configuring Custom WinCC Faceplates and Pop-Up Object Browsers

To present the aggregated bypass status in WinCC:

Compile OS to Export Tags:
* Execute Compile OS (Scope: Changes only).
* The compiler transfers DB500 and its structure tags to the WinCC Tag Management database.
Design the Centralized Overview Graphic in Graphics Designer:
* In Graphics Designer, open or create a pop-up window: @Bypass_Browser.pdl.
* Add a dynamic table or list of text objects representing every interlocked piece of equipment.
* Bind the background color and status icon of each row to the corresponding bit of DB500:
- If Bit = 1: Row turns yellow with a bypass lock symbol and equipment tag.
- If Bit = 0: Row is hidden or displayed in normal grey.
Integrate into CEMAT Overview Toolbar:
* Add a custom button labeled Bypasses to the top menu bar (@Buttons11.pdl or CEMAT toolbar).
* Bind the button click to open @Bypass_Browser.pdl in a floating picture window.

Verification

Verify centralized bypass tracking:
1. In WinCC Runtime, open the faceplate for an interlock block (e.g., Kiln Main Drive Interlock) and set input In01 to Bypass.
2. Confirm that the local block icon displays the blue bypass lock symbol.
3. Click the Bypasses button on the main toolbar:
* Confirm that @Bypass_Browser.pdl immediately pops up.
* Confirm that Kiln Main Drive Interlock is highlighted in yellow, and Total_Bypassed_Count increments from 0 to 1.
4. Remove the bypass: Confirm that the item clears from the list and the counter decrements to 0.

Limitations and Operational Precautions

Manual bypass aggregation requires meticulous engineering discipline; every newly added interlock block must be explicitly interconnected to the central monitoring DB.
Always log all bypass operations in the WinCC Operator Message List with mandatory operator justification comments to comply with audit standards.
When upgrading the facility to PCS 7 V8.2 or V9.x, retire the custom DB500 solution and migrate to the native PCS 7 Bypassed Interlock Browser.

Engineer FAQ

Why was WinCC V7.1 mentioned in the original forum discussion?

Users sometimes mistakenly refer to PCS 7 V7.1 as 'WinCC V7.1'. In reality, PCS 7 V7.1 is bundled with WinCC V7.0 SPx. WinCC V7.1 was never released as a standalone or PCS 7 component.