Adding Secondary AS Controllers with New Libraries into Legacy PCS 7 Projects

In SIMATIC PCS 7 V8.1, you can safely add a new Automation Station (AS2) running modern APL and SENTRON PAC Library V2.1 into an existing multiproject where legacy controllers (AS1) run PCS 7 Standard Library V6.1, without stopping AS1. While mixing different library versions within a single CPU chart folder is strictly prohibited, separate AS controllers maintain independent compilation boundaries. Furthermore, WinCC OS officially supports 'Mixed Operation and Visualization', permitting classic Standard Library faceplates and modern APL/PAC block icons to execute concurrently on the same Operator Station without downtime.

Library Segmentation Rules: Station-Level Isolation vs Program Mixing

A common operational dilemma in expanding operational process plants is integrating new technological functions—such as SENTRON PAC3200 power meters communicating via PROFINET—without forcing a full plant turnaround or CPU STOP on existing controllers running legacy software (such as PCS 7 Standard Library V6.1).

The core engineering rules governing library versions in SIMATIC PCS 7 are:

Never Mix Libraries Inside One AS: Importing blocks from two different major library generations (e.g. Standard Library V6.1 and APL V8.1) into the same S7 Program folder causes block numbering collisions (conflicting FB/FC/DB numbers) and compilation errors in the module driver generator.
Station-Level Independence: Different Automation Stations within the same multiproject can run entirely different library versions. The existing controller (AS1) continues executing Standard Library V6.1 undisturbed, while the newly added controller (AS2) is engineered with modern APL V8.1 and SENTRON PAC Library V2.1.

Mixed Operation and Visualization Architecture in WinCC OS

Beginning with SIMATIC PCS 7 V8.0 and V8.1, Siemens introduced official system validation for Mixed Operation and Visualization of AS Blocks from Different PCS 7 Versions on One OS (detailed in the manual Software Update Without Utilization of New Functions):

The WinCC OS project maintains graphic typicals for both generations:
Classic Standard Library faceplates and icons (@PCS7Typicals.pdl, @FaceplateTypicals.pdl).
Modern APL and PAC Library faceplates and icons (@PCS7TypicalsAPLV8.pdl, @FaceplateTypicalsAPLV8.pdl).
During OS Compilation, the AS-OS engineering engine compiles tags from both stations into the unified WinCC database.
Operators view classic pump/valve faceplates for AS1 alongside modern PAC3200 energy faceplates for AS2 on the same client monitor.

Step-by-Step Procedure to Integrate an Energy Metering AS

Follow this sequence to commission the new controller without impacting running production:

Install PAC Library on Engineering Station: Install the SENTRON PAC Library V2.1 (3ZS2781-1CC11-0YG0) on the ES.
Create New AS in Multiproject:
- In SIMATIC Manager, insert a new SIMATIC 400 Station (AS2).
- Configure hardware (CPU 410-5H or S7-400 with CP 443-1/onboard PN) and connect PAC3200 meters via PROFINET in HW Config.
Build Master Data Library Partition:
- Place SENTRON PAC blocks (PAC_3200 / FB410) and required APL driver blocks into the project's Master Data Library.
Author Logic in AS2:
- Create CFC charts in AS2 and instantiate PAC blocks.
- Compile AS2 charts (Entire program with Generate module drivers).
Execute AS2 Download: Download hardware and software to AS2. Existing controller AS1 remains 100% online.
Perform Delta OS Compilation:
- In SIMATIC Manager, right-click the OS project and select Compile.
- Select Scope: Changes only.
- WinCC compiles the new PAC tags and creates block icons in assigned graphic screens without interrupting active runtime.

PCS 7 Library Generation Compatibility and Visualization Matrix

The following table details compatibility across library generations in a mixed PCS 7 V8.1 environment:

Library FamilyTarget StationSupported in Same AS as APL?WinCC Typical Screen TemplateOS Faceplate StylePCS 7 Standard Library V6.1Existing AS1NO (Forbidden)@PCS7Typicals.pdlClassic gray rectangular faceplatesPCS 7 Advanced Process Library V8.1New AS2YES (Native)@PCS7TypicalsAPLV8.pdlModern APL style with preview viewsSENTRON PAC Library V2.1New AS2YES (APL-based)@PCS7TypicalsPAC_V2.pdlAPL-compliant energy metering viewsIndustry Library (IL) V8.1New AS2YES (APL-based)@PCS7TypicalsILV8.pdlAPL-compliant package unit views

[!NOTE]
Commercial Accuracy Notice: Adding a new controller (AS2) requires purchasing the physical CPU, AS RT Process Object licenses > (or SEC capacity for CPU 410-5H), and SENTRON PAC Library engineering and runtime licenses (3ZS2781-1CC11-0YG0 / 3ZS2781-1CC11-6YH0). > Existing AS1 runtime licenses remain valid and unaffected.

Verification

Verify the mixed-library multi-station operation:

Independent AS Operation: Confirm that AS1 continues running without CPU diagnostic buffer events while AS2 is compiled and downloaded.
OS Runtime Dual Faceplate Test: On a WinCC OS Client, open an existing motor faceplate from AS1 (verify classic look). Then open a PAC3200 meter faceplate from AS2 (verify modern APL styling with active kW/kWh telemetry).
Zero Alarm Conflicts: Inspect WinCC Alarm Logging to confirm that system and process messages from both stations route into their respective plant areas without message ID overlapping.

Limitations and Operational Precautions

Observe these guidelines when operating mixed library environments:

Never Copy Blocks Between AS1 and AS2: Do not cross-copy blocks directly between the chart folders of the two different controllers.
OS Project Editor Preservation: When running the OS Project Editor on WinCC, ensure that both classic typicals and APL typicals are selected in the basic data configuration to prevent overwriting screen templates.
Plan Future Migration: Treat mixed operation as an intermediate upgrade strategy. Plan to modernize AS1 to APL during the next major facility turnaround.

Engineer FAQ

Will adding an APL-based AS2 stop my running Standard Library AS1?

No. Each AS has independent CPU memory, communication links, and compilation pipelines. AS1 remains completely unaffected.

Can WinCC display both classic Standard Library and APL faceplates simultaneously?

Yes. WinCC supports 'Mixed Operation and Visualization'. It renders classic faceplates for AS1 tags and modern APL/PAC faceplates for AS2 tags side by side.

Can I cross-connect an interlock signal from AS1 to AS2 in CFC?

Yes, using standard cross-AS interconnections via NetPro or APL send/receive blocks. However, convert raw BOOL signals to structured data types if linking directly into APL interlock blocks.