Mandatory Conditions for 'Entire Program' Compilation and Download in PCS 7 CFC

In SIMATIC PCS 7 CFC, compiling and downloading 'Changes Only' allows online updates without interrupting controller execution. However, selecting 'Entire Program' compilation is mandatory during initial project commissioning, after modifying hardware configuration memory/address mappings, after updating block type interfaces (inputs/outputs/data types), when modifying chart sampling cycle times across priority classes, or when recovering from internal database fragmentation. For downloading, standard S7-400 CPUs mandate an 'Entire Program' download with the CPU in STOP whenever block structural interfaces change. By contrast, the CPU 410-5H supports Type Change in RUN (TCiR), permitting online downloads in RUN mode even after structural block modifications.

Incremental Engineering: Changes Only vs Entire Program

Continuous process automation facilities operate 24 hours a day, 365 days a year, where unbudgeted controller stoppages result in massive economic loss. To support live facility adjustments, SIMATIC PCS 7 Continuous Function Chart (CFC) features incremental engineering compilers.

The CFC compiler tracks modifications at the block, interconnection, and runtime group level using internal database checksums. Minor modifications (such as altering tuning parameters, adding a new CFC chart, or connecting two existing block pins) permit Compilation of Changes Only and subsequent Download of Changes in RUN. However, specific foundational architectural modifications break internal memory continuity, forcing the compiler to enforce a full compilation of the Entire Program.

Technical Conditions Mandating 'Entire Program' Compilation

An engineer must execute an Entire Program compilation (Chart -> Compile -> Chart as Program -> Entire Program) under the following conditions:

Initial CPU Commissioning: The first compilation of a new S7 Program or newly created AS station.
Hardware Configuration Reallocations: Modifying CPU cycle/clock memory, altering Process Image Partitions (TPA/PIP), or reallocating distributed I/O hardware module addresses.
Block Interface Alterations: Modifying the interface of a Function Block (adding, deleting, or altering data types of inputs, outputs, or static variables) followed by updating block types in CFC.
Runtime Priority Class Restructuring: Re-assigning entire charts between cyclic interrupt OBs (e.g., moving charts from OB35 [100 ms] to OB32 [1 s]).
Database Desynchronization: Recovering from project crashes or corrupted cross-reference lists (ombstx).

Download Constraints and CPU Hardware Differences (S7-400 vs CPU 410)

A critical distinction exists regarding whether a full compilation enforces a CPU STOP during download:

Standard S7-400 Controllers (S7-414, S7-416, S7-417): In standard S7-400 CPUs, modifying a block interface shifts internal instance DB byte offsets. Because the operating system cannot dynamically relocate memory structures in active memory, the CFC loader blocks Changes Download in RUN. The user is forced to execute an Entire Program Download, requiring transitioning the CPU into STOP mode.
SIMATIC CPU 410-5H (Type Change in RUN - TCiR): The dedicated PCS 7 flagship controller CPU 410-5H incorporates patented firmware architecture supporting TCiR (Type Change in RUN). On CPU 410-5H, even after an Entire Program compilation resulting from modified block interfaces, the updated blocks and instance DBs can be downloaded online while the controller remains in RUN mode without interrupting process control.

Compilation and Download Scenario Matrix

The following table summarizes compilation scopes, download permissions, and required CPU operating modes:

Engineering Modification EventRequired Compile ScopeStandard S7-400 Download ModeCPU 410-5H Download ModeParameter Value Change / Link ModificationChanges OnlyRUN (Changes Download)RUN (Changes Download)Adding New CFC Chart / New Block InstanceChanges OnlyRUN (Changes Download)RUN (Changes Download)Block Interface Modified (Pin Added/Deleted)Entire ProgramSTOP Mandatory (Entire Program)RUN Permitted (TCiR)HW Config Process Image ExpandedEntire ProgramSTOP Mandatory (Entire Program)RUN Permitted (via CiR)Moving Chart Between OB35 and OB32Changes / EntireRUN (Changes Download)RUN (Changes Download)Corrupted CFC Database RecoveryEntire ProgramSTOP Mandatory (Memory Reset)RUN (If memory intact)

Verification

Verify compilation and download success:
1. Confirm that the compilation log finishes with: 0 Errors, 0 Warnings.
2. Verify the CPU operating mode: Green RUN LED solid; zero system fault (SF) or bus fault (BF) LEDs.
3. In CFC, open dynamic display mode online. Confirm that live values and calculations update cyclically.
4. Check the CPU Diagnostic Buffer to verify that no memory reallocation errors or OB call faults are logged.

Limitations and Operational Precautions

CFC Readback Precaution: Before performing an Entire Program download that requires a CPU STOP, always execute Chart -> Readback to preserve operational setpoints and tuning parameters modified by operators at runtime.
TCiR CPU 410 Memory Limits: TCiR requires sufficient spare work memory in the CPU 410-5H to buffer both old and new block instances simultaneously during online relocation.
Redundant H-System Coupling: On S7-400H systems, hardware modifications require Configuration in RUN (CiR) pre-allocation to avoid stopping the redundant pair.

Engineer FAQ

Can an Entire Program compilation ever be downloaded to an S7-400 in RUN?

If the full compilation was triggered purely by compiler flags or reorganization without altering block interfaces, a Changes-Only download in RUN may still be accepted by the S7-400. If interfaces changed, STOP is mandatory.

What is Type Change in RUN (TCiR)?

TCiR is a patented Siemens feature available on CPU 410-5H controllers that allows loading modified block type interfaces into the CPU online without putting the controller into STOP.

Why did CFC force an Entire Program compile after updating block types?

Because modifying a block definition changes instance DB lengths across all charts, invalidating incremental compilation tracking.

What happens to plant I/O during an Entire Program download in STOP?

When the CPU enters STOP, all digital and analog outputs transition to their configured safe resting states (0V, 4mA, or hold last value), immediately halting field actuators.