Compare a PCS 7 CFC Chart with the Live AS Program

To check whether a PCS 7 engineering chart matches the program in the AS, use CFC's online-mode comparison for the chart belonging to that AS. Treat “Program change since the last compilation” as a mismatch to investigate, not as an instruction to compile and download immediately. VXM can help compare engineering project revisions, but the cited Siemens manuals describe that separately from a live CPU-to-engineering comparison.

What the CFC message means

The message indicates a difference relevant to the online/offline comparison since compilation. Siemens' PCS 7 engineering guidance says to open a chart from the AS in CFC and switch to online mode to check whether the offline chart and AS program correspond. A mismatch should be investigated before making further changes; the message alone does not identify the changed block, chart element or parameter.

Compare the live AS with the engineering project

For the live comparison, use CFC's online mode with the chart belonging to the AS. Siemens documents that a comparison check occurs as part of switching to online mode: CFC reports a difference when the versions are not identical. The available manufacturer material does not establish a universal detailed difference viewer or exact click sequence for every CFC release, so use the documentation installed for the exact PCS 7/CFC version to inspect the comparison result.

Use VXM for project-version comparisons

VXM addresses a different comparison: it compares engineering project versions, such as the current project and a backup, and identifies project-level changes in supported objects. It does not itself establish a direct comparison between a live CPU's current program and the open engineering project. Use VXM when the question is which engineering project revision changed, then use the applicable CFC online comparison to assess the AS.

Safe investigation sequence

Preserve the current project and obtain the site's approved backup or baseline before changing anything.
Confirm the selected AS and open its relevant chart in CFC; switch to online mode using the procedure documented for the installed PCS 7/CFC version.
Record the mismatch and identify what changed through the available version-specific comparison facilities. If necessary, compare the engineering project against a known backup with VXM.
Establish which version is authoritative with the responsible controls engineer and review operational and safety impact.
Only after the difference is understood and an approved change plan exists, decide whether to edit, compile or download. A compile/download recommendation from an informal reply is not enough to establish that those actions are safe or correct.

Safety-signature considerations

For failsafe functions, Siemens' PCS 7 Compendium Part B describes checking that the last compilation signature matches the online signature. If signatures differ or a warning appears, determine the changes and whether they can be downloaded before proceeding. Apply the instructions for the actual release and configured safety system; do not treat a matching signature as a substitute for the site's required safety review.

Verification

Confirm that the online comparison is for the intended AS and chart and that the result is understood. When relevant, compare the engineering project with an approved baseline using VXM. For failsafe applications, check the applicable online and last-compilation signatures. Before any authorized download, verify the planned change against the project's change-control and commissioning requirements.

Limitations and Operational Precautions

The cited Siemens guidance is for PCS 7 V9.0 documentation; the ticket does not state its PCS 7 or CFC version, AS type, or provide the referenced attachment. The exact detailed display for locating individual differences is therefore version-dependent and cannot be specified from the available evidence. Siemens CFC V9.0 SP5 Update 5 documentation also flags unreliable online/offline comparisons for certain SFC type actions or conditions that use commands or states; check that readme if this setup applies. Do not compile or download merely to clear a warning when the difference is not understood, particularly on a running or safety-related system.

Engineer FAQ

Does this warning identify the exact change? No. It reports a mismatch condition; the evidence reviewed does not say the message itself identifies the changed object.

Can VXM compare the CPU directly with the ES? The cited Siemens VXM documentation describes comparing two engineering project versions, not a direct live CPU-to-ES comparison.

Should I immediately compile and download? Not solely because the warning appears. Determine and approve the differences first.

Does this method apply to every PCS 7 release? Confirm the applicable CFC procedure and limitations in documentation for the installed release.

What additional information is needed for exact steps? PCS 7/CFC version and update, AS type, the complete warning or attachment, and whether safety-related SFC features are involved.