Diagnosing SIMATIC PCS 7 AS Download Error (1739:60458): Delta Download Invalidation and CP 1623 NDIS Conflicts

SIMATIC PCS 7 AS download error '(1739:60458)' indicates that changes cannot be downloaded to the automation station in RUN mode and that an entire download (requiring an AS STOP) is demanded. This occurs primarily due to two distinct mechanisms: either the CFC internal compilation database timestamp or block allocation tables were desynchronized (forcing a complete download), or a low-level network layer conflict exists on the Engineering Station's communication processor (such as a CP 1623 with identical MAC addresses between ES and standby server, or duplicate IP configurations between NDIS and Industrial Ethernet protocols). Correcting CP 1623 configuration or restoring the prior consistent project archive restores download functionality without halting the plant.

Mechanics of Error 1739:60458 and Delta Download Invalidation

In a running chemical or manufacturing facility, process engineers rely on Delta Download (Download Changes in RUN) to commission logic revisions, tune PID controllers, and add interlocks without halting the production process. When an engineer clicks download after compiling changes and is confronted with error (1739:60458) Download changes is not possible. A complete download is necessary, the situation is critical because a complete download requires transitioning the AS CPU into STOP mode, shutting down active operations.

The error dialog indicates that the online AS operating state or network communication pathway cannot accept the delta change sequence calculated by the CFC compiler.

Root Cause 1: CP 1623 MAC Address Duplication and NDIS/IE Conflicts

A pervasive cause of error 1739:60458 on PCS 7 V8.0, V8.1, and V8.2 systems involves hardware communication processors such as the SIMATIC CP 1623 or CP 1613:

MAC Address Duplication: When an ES or OS image is cloned (e.g., using Acronis or virtual machine snapshots), the locally administered MAC address configured in the Siemens Communication Settings may be cloned onto both the ES and a standby OS Server. When both stations connect to the Plant Bus, layer-2 switch port flapping causes communication packets to be corrupted, dropping the AS download handshake mid-stream.
NDIS / Industrial Ethernet IP Conflict: The CP 1623 supports both native Industrial Ethernet (ISO transport) and standard Windows TCP/IP networking via an NDIS driver. If an engineer accidentally assigns identical or conflicting IP configurations to both the NDIS interface and the Industrial Ethernet protocol stack, the S7 online communication driver fails during block verification.

Root Cause 2: CFC Database Timestamp Skew and Block Allocation Loss

If the network layer is healthy, error 1739:60458 points directly to an internal CFC database discrepancy:

Compilation Timestamp Inconsistency: When changes are compiled, CFC compares the offline chart modification dates with the compile logs stored in the project's internal database. If files were edited outside CFC, if a block type was updated with an altered interface without structural migration, or if an older project version was partially restored, the delta tracking chain is broken.
Work Memory or DB Number Exhaustion: If the change requires allocating an instance DB in an AS memory segment that is fragmented or full, the AS rejects the online insertion, demanding a full compaction via entire download.

Step-by-Step Diagnostic and Remediation Procedure

To resolve error 1739:60458 without an unscheduled plant shutdown:

Audit CP 1623 Configuration: On the ES, open SIMATIC NET > Communication Settings (or 'Set PG/PC Interface').
- Verify that the CP 1623 MAC address is unique and matches the factory hardware MAC printed on the card label.
- Check the NDIS settings. Ensure the NDIS network interface is either disabled or assigned a distinct, non-conflicting IP subnet.
Check Diagnostic Buffer: In SIMATIC Manager, connect to the CPU and open Module Information > Diagnostic Buffer. Inspect the exact event leading up to the download rejection (e.g., memory bottleneck, OB error, or connection reset).
Compare Offline and Online Charts: Select Options > Compare > Software and Hardware. Review the delta changes.
Revert to Pre-Incident Project Archive: If the timestamp chain was damaged by an incomplete compile, retrieve the verified project backup taken before the modification. Apply only the necessary logic edits and recompile changes.
Execute Delta Compile and Delta Download: In CFC, select Charts > Compile > Changes only. Then select PLC > Download > Changes only. Verify that the AS accepts the delta block stream.

Delta Download vs Full Download Failure Scenarios

The following table compares conditions leading to delta download invalidation versus recoverable network issues:

Diagnostic ScenarioUnderlying Root CauseImpact on AS OperationCorrective Action PathCP 1623 MAC ConflictDuplicate MAC on Plant Bus switchCommunication drops during downloadSet unique MAC in SIMATIC NET settings; no AS stop neededNDIS Protocol CollisionOverlapping IP on CP 1623 NDIS driverTransport layer socket abortUnbind NDIS or separate subnet; no AS stop neededBlock Interface ChangeInput/output added to FB in useDelta download permanently blockedRevert FB interface or schedule AS STOP downloadTimestamp InconsistencyCharts compiled against mismatched libraryCompiler cannot trace delta stepsRestore pre-compile project backup and recompileMemory FragmentationAS RAM work memory full or fragmentedCPU cannot allocate new instance DBReorganize runtime groups or execute memory compress

Verification

Confirm that download capability is restored through the following steps:

In SIMATIC Manager, select PLC > Set PG/PC Interface. Ensure S7ONLINE is pointed to CP1623(ISO) or CP1623(RFC1006).
Make a non-intrusive test change in a test CFC chart (e.g., modify an inverted pin or comment).
Execute Charts > Compile > Changes only. Ensure compilation finishes with zero errors.
Execute PLC > Download > Changes only. Confirm that the download dialog shows 'Download changes' enabled and finishes without prompting for an entire download.

Commercial Accuracy Disclaimer: Software order numbers (MLFBs), package structures, and hardware capacity prerequisites vary across PCS 7 versions and hardware platforms. System integrators must confirm exact software entitlements and licensing requirements against the official Siemens Catalog CA 01 and obtain an authorized Siemens distributor quotation prior to purchasing.

Limitations and Operational Precautions

Consider these operational rules when troubleshooting AS downloads:

Never Click 'Yes' to an Entire Download on a Running Plant: If the dialog prompts 'Download entire program? This will transition the CPU to STOP', clicking Yes will immediately trip all active drives, close control valves, and crash the plant.
Always Archive Before Changing Logic: Execute a fast project archive (File > Archive) before making CFC modifications so a clean baseline is available if delta tracking becomes corrupted.
Firmware Version Parity: In redundant S7-400H or CPU 410-5H systems, ensure both redundant CPUs run identical firmware versions; mismatched firmware can prevent delta synchronization between sub-racks.

Engineer FAQ

What is the NDIS protocol on a Siemens CP 1623 card?

NDIS is the standard Windows network driver interface that allows the CP 1623 to function as a general-purpose Windows Ethernet NIC alongside its specialized industrial protocol processor.

How do I avoid breaking Delta Download capability during block type updates?

When updating block types, use the 'Update Block Types' wizard and ensure that existing block interface structures are not altered in a way that shifts parameter offsets.

Can CPU 410-5H accept larger delta changes than older S7-400 CPUs?

Yes, the CPU 410-5H features significantly larger work memory and optimized delta loading algorithms, making delta downloads substantially faster and more resilient against memory fragmentation.