How to Remove Orphaned Power Supply Address Gaps and '?' Entries in S7-400H Hardware Configurations

In SIMATIC PCS 7 redundant S7-400H systems, the HW Config error 'Unable to find object' accompanied by peripheral addresses marked with '?' in the Address Overview indicates that orphaned diagnostic address allocations exist for power supply modules across Rack 0 and Rack 1. When power supply modules (such as PS 407 10A) are inserted, deleted, or reassigned, legacy diagnostic interrupt byte reservations can remain orphaned in the internal hardware database tables. To remove these four ghost address reservations without executing a full project reorganization, engineers must open the Address Overview, identify the offending diagnostic addresses, temporarily disable or realign diagnostic interrupts in the power supply module properties on both racks symmetrically, and compile the station.

Forensic Analysis of '?' Address Gaps in S7-400H Address Overview

In SIMATIC S7-400H fault-tolerant systems, hardware consistency checking enforces strict symmetrical hardware address alignment between Rack 0 and Rack 1:

The Problem: In HW Config, executing Station > Check Consistency halts with: Unable to find object.
The Address Overview Inspection: Navigating to View > Address Overview reveals four contiguous or split input address bytes (often in the high address range, such as bytes 16380 to 16383) marked with a question mark ? under the Rack and Slot columns.
Why the '?' Appears: The question mark signifies an allocated address block in the peripheral process image table that has no corresponding, physically instantiated hardware module linked to it in the station layout. The compiler encounters an orphaned pointer, causing compilation to abort.

Power Supply Diagnostic Addressing Architecture on Redundant Racks

The reason exactly four addresses appear orphaned is tied directly to redundant power supply topology:

S7-400H Redundant Power Supply Design:
Fault-tolerant systems typically deploy two power supply modules in Rack 0 (Slots 1 and 2) and two power supply modules in Rack 1 (Slots 1 and 2)—a total of four power supplies (PS 407 10A 6ES7407-0KA02-0AA0 or PS 405 10A 6ES7405-0KA01-0AA0).
Diagnostic Interrupt Addressing:
Each power supply supports diagnostic addressing to report AC power loss, DC 24V/5V failure, or backup battery exhaustion to the CPU via OB82 (Diagnostic Interrupt).
If an engineer previously checked Diagnostic Interrupt and subsequently deleted or replaced one of the modules, the address assignment table can retain the old byte reservations while the graphical rack shows empty or misaligned boxes.

Clearing Orphaned Ghost Addresses Without Project Reorganization

To eliminate these orphaned addresses without performing Save As with Reorganization (Slow):

Open HW Config for the S7-400H Station:
* Open HW Config in SIMATIC Manager.
* Open View > Address Overview.... Note the exact byte numbers showing ? (e.g., 16380, 16381, 16382, 16383).
Realign Power Supply Properties on Rack 0:
* In Rack 0, double-click the first Power Supply module (Slot 1).
* Open the Addresses tab.
* If diagnostic addressing is enabled, note the address. If disabled, temporarily check Diagnostic Interrupt and assign it explicitly to the first orphaned address (e.g., 16380).
* Double-click the second Power Supply module (Slot 2) on Rack 0: assign it to 16381.
Realign Power Supply Properties on Rack 1:
* Double-click the third Power Supply module (Rack 1, Slot 1): assign to 16382.
* Double-click the fourth Power Supply module (Rack 1, Slot 2): assign to 16383.
Disable Diagnostic Addressing Cleanly (If Desired):
* If diagnostic interrupts are not needed, open each module again, uncheck Diagnostic Interrupt, and click OK.
* The explicit assignment and subsequent de-selection forces HW Config to write a clean zero-allocation record to the internal peripheral table, instantly wiping out the ghost ? entries.
Execute Consistency Check:
* Select Station > Check Consistency. Verify that the compiler reports 0 Errors.

CFG Export and Sanitize Procedure for Persistent Database Locks

If internal relational table corruption prevents HW Config from clearing the address pointers:

Export Station as CFG:
* Select Station > Export....
* Choose export format: Readable (CFG file) and save as S7_400H_Clean.cfg.
Sanitize CFG in Text Editor:
* Open S7_400H_Clean.cfg in Notepad++.
* Search for the offending address bytes (e.g., 16380).
* Delete the orphaned _DIAG_ADDRESS parameter lines that lack valid module parent references.
Import and Recompile:
* Create a new temporary station in SIMATIC Manager.
* Open HW Config: select Station > Import... and select S7_400H_Clean.cfg.
* Compile and save: the hardware configuration will compile with 100% clean consistency.

Comparison of S7-400H Address Table Diagnostic Symptoms

The table below outlines common address allocation anomalies in STEP 7 HW Config.

Symptom / Symbol in Address ViewRoot CauseUnderlying Table ImpactResolution WorkflowContiguous bytes with '?'Orphaned diagnostic address assignmentResidual record in peripheral imageReassign and uncheck diagnostic interruptsEmpty box in rack viewGraphics descriptor missing or corruptVisual rendering desynchronizationClose HW Config, reopen or reinstall HSPDuplicate address conflict red flagTwo modules assigned overlapping I/OPeripheral address overlap in process imageManually renumber start addresses'Unable to find object' compiler haltAsymmetric rack alignment in S7-400HCross-rack partner pointer severedAlign Rack 0 and Rack 1 module propertiesTable lock on YLinklist during SaveBackground Windows process holding DBWindows .lck file in project YDBSRun reset_wincc.vbs, delete .lck files

Verification

To confirm that the power supply ghost addresses are resolved:
1. In HW Config, select View > Address Overview....
2. Scroll through the Inputs and Outputs tables: confirm that zero entries display with a question mark ? in the Rack or Slot columns.
3. Select Station > Check Consistency. Confirm the message box returns: Check consistency: 0 Error(s), 0 Warning(s).
4. Execute Station > Save and Compile. Confirm that System Data Blocks (SDBs) generate successfully into the CPU block container.
5. In SIMATIC Manager, perform a delta compile of CFC charts: verify module driver generation succeeds without address generation errors.

Limitations and Operational Precautions

Never download an S7-400H hardware configuration containing consistency errors to an active production plant; inconsistent SDBs can trigger unexpected controller stops or redundant partner rejection.
If making hardware changes online via H-CiR (Configuration in RUN), ensure that both sub-racks remain synchronized in RUN mode throughout the download sequence.
Before editing raw .cfg text exports, always preserve an uncompressed master archive of the original multi-project.
Always validate final hardware modules, power supplies, and ordering numbers against the applicable Siemens catalog and authorized distributor quotation.

Engineer FAQ

Why did the power supplies show as empty boxes in HW Config?

An empty box appears when HW Config has an address record registered in the station database, but the graphical symbol definition cannot find its corresponding catalog metadata, typically caused by deleting the module without releasing its diagnostic addresses.

Can I just ignore the '?' in Address Overview if the plant runs?

No. While an already-loaded controller may continue running on older compiled SDBs, HW Config will strictly block any future hardware compilation or downloads until consistency errors are resolved.

Does assigning diagnostic addresses consume controller I/O memory?

Diagnostic addresses reside outside the cyclic process image partition (typically in high memory, e.g., above byte 16380) and do not consume standard process image partition (PIP) space.