Migrating PCS 7 V8.2 to V9.0 Without Updating AS Controller Libraries and Module Drivers

In SIMATIC PCS 7, migrating an engineering environment and Operator Stations from PCS 7 V8.2 to V9.0 while deliberately preserving legacy Basis Library V8.2 and APL V8.2 on running automation controllers is officially supported using the "Software Update Without Utilization of New Functions" workflow. To maintain older AS libraries on a PCS 7 V9.0 Engineering Station without compilation errors, engineers must install the legacy PCS 7 Basis Library V8.2 and APL V8.2 software packages onto the V9.0 ES from original media. Crucially, APL and Basis Library versions within an AS must remain strictly identical: updating APL to V9.0 while holding Basis Library at V8.2 causes module driver generator crashes.

Software Update Strategies: With vs Without New Functions

When upgrading an existing SIMATIC PCS 7 plant from V8.2 to V9.0 (to take advantage of Windows 10 OS clients, modern WinCC features, or updated virtualized server hardware), plant management frequently demands that the active controllers remain untouched to avoid production outages.

Siemens system documentation formally distinguishes two migration pathways:
1. Software Update With Utilization of New Functions: Both ES/OS and AS controllers are upgraded to V9.0. All blocks are updated to APL V9.0, module drivers are regenerated using Basis Library V9.0, and new hardware (e.g., ET 200SP HA) is supported. This requires a full CPU STOP download.
2. Software Update Without Utilization of New Functions: The ES and OS are upgraded to V9.0, but the AS controllers retain their existing V8.2 runtime programs. Controllers continue executing without modification, and downloads can proceed online in RUN mode.

Why APL and Basis Library Versions Must Remain Aligned

A critical architectural rule governs PCS 7 library management:

Library Combination in ASCompiler FeasibilityModule Driver BehaviorRisk / StabilityBasis Library V8.2 + APL V8.2Fully Supported (Without New Functions)Drivers generated cleanly using V8.2 templatesHigh stability; no CPU STOP requiredBasis Library V9.0 + APL V9.0Fully Supported (With New Functions)Drivers generated using modern V9.0 templatesFull V9.0 features; requires CPU STOPBasis Library V8.2 + APL V9.0FATAL CONFLICT (Unsupported)S7JS7CAX.EXE crashes; signature mismatchesCompilation aborted; project corruption

The module driver generator relies on synchronized interfaces between APL channel drivers (Pcs7DiIn) and Basis Library diagnostic drivers (MOD_D...). Mixing APL V9.0 with Basis Library V8.2 creates severe parameter interface mismatches that cause the compiler to crash.

Installing Legacy Libraries on a PCS 7 V9.0 Engineering Station

To allow a PCS 7 V9.0 Engineering Station to compile and maintain V8.2 controllers:

Install the baseline SIMATIC PCS 7 V9.0 software suite on the Engineering Station.
Insert the legacy SIMATIC PCS 7 V8.2 DVD (or download the legacy library packages from Siemens Industry Online Support).
In the setup launcher, select Custom Installation and choose ONLY:
- PCS 7 Basis Library V8.2
- PCS 7 Advanced Process Library V8.2
Complete the installation.
In SIMATIC Manager, select File -> Open -> Libraries; verify that both PCS 7 Basis Library V8.2 and PCS 7 Basis Library V9.0 exist side-by-side in the system library catalog.

Handling Module Drivers and AS Compilation Rules

When maintaining the V8.2 AS program inside PCS 7 V9.0:
1. In the Multiproject, ensure that the Master Data Library contains exclusively V8.2 blocks. Do NOT copy V9.0 blocks into this library.
2. Do NOT run 'Update Block Types' with V9.0 blocks.
3. When compiling CFC:
- The CFC compiler identifies that the blocks belong to library version 8.2.
- The compiler automatically invokes the installed V8.2 module driver generator routines, updating @ diagnostic charts without introducing V9.0 signatures.
4. Changes can be downloaded to the CPU in RUN mode (Changes only).
5. For the Operator Station, run OS Project Editor and compile the OS to generate updated WinCC V7.4 SP1 runtime packages.

Verification

To verify that legacy AS compatibility is maintained:
1. In SIMATIC Manager, open the S7 Program block folder; inspect block properties of MOD_D8 and Pcs7DiIn; verify that block versions read 8.2.
2. Compile CFC with 'Generate module drivers' (Changes only); verify that compilation finishes with 0 Errors.
3. Download changes to the S7-400 CPU in RUN mode; verify that the CPU remains in RUN without diagnostic alarms.
4. Open WinCC Runtime on an OS Client; verify that APL faceplates open, display live data, and control field equipment normally.

Limitations and Operational Precautions

If new V9.0 hardware components (such as SIMATIC ET 200SP HA interface modules or Compact Field Units) are subsequently added to the project, the controller MUST be upgraded to Basis Library V9.0. Legacy Basis Library V8.2 does not contain driver blocks capable of evaluating ET 200SP HA diagnostic data records. Retaining V8.2 libraries is strictly intended for maintaining existing hardware racks.

Engineer FAQ

Can an OS running PCS 7 V9.0 communicate with a CPU running APL V8.2?

Yes. PCS 7 V9.0 OS servers and clients are fully backward-compatible with automation programs running APL V8.2 and V8.1.

Will opening a V8.2 project in PCS 7 V9.0 automatically upgrade the blocks?

No. Opening the project converts the project database format, but block types inside the charts are only upgraded if you explicitly execute 'Update Block Types'.

Can I upgrade one AS to V9.0 while keeping another AS at V8.2 in the same Multiproject?

Yes. Each AS program inside a Multiproject can maintain its own independent library version, provided each project's Master Data Library is managed correctly.