Does PCS 7 V8.2 Limit CPU 416-5H to 31 Redundant I/O Cards?

The available evidence does not establish a PCS 7 V8.2 limit of 31 redundant I/O cards on a CPU 416-5H. The report says compilation succeeds with 31 cards and fails after enabling redundancy on card 32, but the moderator closed it as a duplicate and provided no diagnosis. Siemens specifies a maximum FC size of 64 KByte for the CPU; that code-size limit does not define a card-count limit. Diagnose the exact compiler output and generated function before changing the configuration.

What the Report Shows

The project is reported as PCS 7 V8.2 with a CPU 416-5H, 33 failsafe redundant cards (5 AI, 11 DO and 17 DI), and a compile error after redundancy is enabled on the thirty-second card. The author says the configuration is in OB1 and there is no user logic. The thread was closed because the same question had been posted elsewhere. It contains no full compiler log, exact CPU/firmware information, I/O module part numbers, driver versions, or resolution.

Why 31 Is Not a Published Capacity Limit

The separate 64 KByte figure cited for CPU 416-5H is a maximum function size in Siemens' S7-400H Instruction List. It is not a limit on the total number of redundant I/O cards. Generated CFC or module-driver code can depend on the selected modules and project configuration, but this duplicate thread does not show which function failed or what code was generated. The observed 31/32 boundary cannot be generalized to other projects.

Troubleshooting the Compile Failure

Save a backup copy of the project and preserve the complete compile log with the exact message, implicated function, station and compile phase.
Record CPU order number and firmware, PCS 7 V8.2 update level, driver/library versions, exact module order numbers and redundancy configuration.
Identify whether the error names a maximum code-area or function-size condition and determine which generated or user function is implicated. The thread supplies no function identifier.
Compare the hardware configuration and generated driver blocks with documentation for the installed PCS 7 and module-driver versions. Do not infer that the 32nd card is individually defective or that the project has a 31-card capacity.
If version-specific documentation does not resolve the diagnostic, provide the evidence to Siemens support or the responsible PCS 7 specialist for project-specific assessment.
Recompile after any reviewed change and examine the full result. Assess the effect of changes to cyclic task assignment, generated drivers and failsafe configuration before any live download.

Treat the Duplicate Closure as Editorial Context

The moderator's message confirms only that the same question was posted twice and directs the reader to the other discussion. It does not confirm a technical cause or answer whether a maximum card count exists. The duplicate thread therefore cannot support a fix or a quantified limit.

Verification

Confirm that the compiler log identifies a code-area or function-size diagnostic and names the relevant function. After a version-supported correction, recompile and verify that the same diagnostic is gone and that required redundant I/O and driver assignments remain. Check all remaining warnings and validate safety-related configuration through the plant's approved engineering process. An offline compile result alone does not certify the failsafe application.

Limitations and Operational Precautions

No supported card-count maximum or confirmed remedy appears in the thread. PCS 7 V8.2 is named, but CPU firmware, driver version and module identities are missing. The CPU's FC code-size specification must not be presented as a count of cards. Do not change PLC memory settings, modify generated code or download to a live controller based on this closed duplicate thread.

Engineer FAQ

Does the 32nd card exceed a PCS 7 card limit? The source does not prove that. It records when this project's compile error appeared, not a manufacturer-defined count.

Did the moderator identify the root cause? No. The moderator only closed the discussion as a duplicate.

What does the 64 KByte figure apply to? Siemens specifies it as an individual FC size limit for CPU 416-5H, not as a redundant I/O capacity.

What information is missing? The full diagnostic, implicated function, CPU order number and firmware, PCS 7 update, driver package, module types and generated configuration details.

Is there a confirmed fix? No. Obtain a project-specific diagnosis before changing memory settings, generated blocks or safety-related hardware configuration.

Technical References

Siemens, S7-400H Instruction List, 07/2012, A5E01359153-03, function (FC) size specification for CPU 416-5H: https://support.industry.siemens.com/cs/attachments/63012499/Operationsliste_S7-400H_b.pdf
Siemens, PCS 7 Compendium Part A – Configuration Guidelines, V9.0, 03/2018, p. 185, runtime-group restructuring discussion for a specific CFC block-size situation; it does not establish a remedy or card limit for this thread: https://support.industry.siemens.com/cs/attachments/109756485/pcs7_compendium_part_a_en-US_en-US.pdf