How to Resolve a PCS 7 CFC Compile Error That Names CH

How to Resolve a PCS 7 CFC Compile Error That Names CH_AI

If PCS 7 reports “Necessary files are missing for block CH_AI” while compiling a project that uses Pcs7AnIn, inspect the CFC project's stored block types before installing another I/O library. In one reported PCS 7 V9.0 case, using CFC's Options > Block Types > Clean Up resolved the message. Siemens documents this function for removing unused block types; it does not document it as a specific CH_AI error fix.

What the CH_AI Message Tells You

The diagnostic explicitly names CH_AI. That identifier is distinct from the APL channel-driver block Pcs7AnIn mentioned in the configuration. The reported project produced the CH_AI message even after the engineer selected Pcs7AnIn, and the subsequent CFC cleanup cleared it. This points to a remaining CH_AI type record in the project's CFC data as a plausible explanation, but the exact internal cause was not independently established. The message alone does not establish that a VIPA library is missing.

Why Cleanup Can Be Relevant

Siemens' CFC for SIMATIC S7 (V9.0 SP5) Function Manual, section 10.5.8, describes cleanup of block types that are no longer required. The first cleanup dialog lists block types in the CFC chart folder that have no instances in charts. The second lists types in the offline block folder that are not in the chart folder; Siemens notes that types called by other blocks can appear there. This is a documented way to remove unused types, not a manufacturer-confirmed diagnosis for every CH_AI compile message.

Before You Remove Any Block Type

Save or back up the project using the site's approved project-management procedure. Confirm the affected project and its CFC version, then inspect whether CH_AI is still used by a chart or called as a dependency. Cleanup can delete selected block types from the chart or block folder. Do not remove a type merely because its name looks old; review the listed types and dependencies, especially in the second dialog.

Run CFC Block-Type Cleanup

Open a CFC chart in the affected project.
Open Options > Block Types....
Use Clean up to open the cleanup dialogs.
Review the listed block types in the first dialog. It is for types in the chart folder that have no block instances in charts. Select only types confirmed as unnecessary for this project.
Review the second dialog carefully. It lists types in the offline block folder that are not in the chart folder and can include types called by other blocks. Do not delete a listed dependency unless the project review confirms it is not required.
Confirm the selected removals in each dialog, then compile again and inspect the full compile results.

The menu path and the two-dialog behavior are documented for CFC V9.0 SP5. The ticket reports that this cleanup resolved the CH_AI message in that particular project.

Keep the I/O Configuration Question Separate

CFC block-type cleanup addresses project block-type entries. It does not configure PROFINET hardware or establish that a particular VIPA SLIO station, module, GSD/GSDML file, firmware, or PCS 7 configuration is supported. Check the device-specific hardware configuration and the manufacturer's applicable device documentation separately. The compile diagnostic naming CH_AI is not, by itself, evidence that a VIPA-specific library is required.

Verification

After cleanup, compile the relevant charts again and confirm that the CH_AI missing-files message no longer appears. Review all remaining compile diagnostics and confirm that the intended Pcs7AnIn instance is present and configured for the intended channel. Then verify the hardware configuration and I/O exchange using the approved project and commissioning checks. A successful compile alone does not prove that the remote I/O is correctly configured or communicating.

Limitations and Operational Precautions

The exact reason CH_AI remained in the reported project was not established. The successful cleanup is a source-reported result for one PCS 7 V9.0 case, not a guarantee for other projects. The cited cleanup instructions apply to CFC V9.0 SP5; confirm behavior against the installed CFC release if it differs. Removing a needed block type or dependency can affect engineering data, so preserve a recoverable project copy and inspect each candidate before deletion. No VIPA model-specific compatibility conclusion is made here.

Engineer FAQ

Does the message prove that a VIPA library is missing? No. It names CH_AI, while the ticket says the project used Pcs7AnIn. The message alone does not identify a VIPA library requirement.

Does Siemens say cleanup fixes every CH_AI error? No. Siemens documents cleanup of unused block types; the reported resolution is from this one project.

Can I delete every type shown in the cleanup dialogs? No. Review the candidate types and dependencies. The second dialog can contain types called by other blocks.

What should I check if the message remains? Determine whether CH_AI is still referenced by charts or dependencies and inspect the exact compile context and project libraries for the installed CFC/PCS 7 versions.

Does a successful compile verify the VIPA remote I/O? No. Verify the hardware configuration and actual I/O communication separately.

Technical References

Siemens, CFC for SIMATIC S7 (V9.0 SP5), Function Manual, 11/2020, A5E41356073-AF, section 10.5.8, “How to delete block types,” pp. 119–120. Open the Siemens manual.

Related Tags

PCS 7, CFC, PROFINET, remote I/O

How to Resolve a PCS 7 CFC Compile Error That Names CH_AI