Fixing TIA Portal V11 SP2 S7-1200 Offline/Online Mismatch on Feb

Problem Overview

Engineers commissioning SIMATIC S7-1200 controllers with TIA Portal V11 SP2 report a confusing failure mode in which a project downloads successfully the first time and online monitoring works against every block, but as soon as the project is edited, recompiled, and re-downloaded the engineering station claims that every block on the CPU is "different" from the offline copy. The compare editor reports zero textual or graphical differences, yet the blue/orange "modified" indicator remains on every block. Attempting to upload from the CPU back to the programming device crashes the TIA Portal application with a non‑responding process and a generic Windows error dialog. New projects created locally and downloaded for the first time exhibit the same behavior, ruling out a corrupt source archive.

The defect is a date-handling bug in TIA Portal V11 SP2 that manifests whenever the Windows system clock on the engineering station is set to a leap day, 29 February. It is reproducible across CPUs from the S7-1200 family (CPU 1211C, 1212C, 1214C, 1215C, 1217C) with firmware V2.2 through V3.0.2 when compiled with TIA V11 SP2 or any earlier V11 service pack that ships the same offline/online reconciliation engine. CPU 1214C AC/DC/Relay is the most commonly affected variant because it is the default training and pilot machine used by integrators.

Affected Versions and Products

Symptoms in Detail

The failure presents three independent observable symptoms. Engineers usually see them in this order:

1. Universal "different" indicator. After a download, every block (OB1, FBs, FCs, DBs, system data blocks) carries the blue/orange "modified in offline" marker even though the offline project was just downloaded to the CPU. The compare editor (Online > Compare offline/online) opens, walks through every block, and reports "No differences" for each.
2. Upload crash. Selecting Online > Upload from device causes TIA Portal to stop responding. The application raises an internal error dialog followed by the Windows "this program is not responding" prompt. Closing the program loses any unsaved local edits.
3. Round-trip corruption. Creating a brand-new project offline, compiling it cleanly, and downloading it to a freshly reset CPU still yields the modified indicator after download. The defect therefore is not caused by a stale online copy of the previous project.

Secondary symptoms include but are not limited to: inconsistent system clock on the CPU versus the project, missing or duplicated timestamps in the diagnostic buffer, the Go online dialog reporting a different TIA Portal version between the project and the connected CPU, and the Accessible nodes view returning no device when PROFINET name resolution is enabled.

Root Cause: The 29 February Date Bug

TIA Portal V11 SP2 stores the offline compilation timestamp and the online block checksum alongside the Windows local date. The reconciliation routine that decides whether a block is "modified offline vs. online" computes a normalized date token that is fed into a 16-bit day counter. On leap day the routine casts 29/02/yyyy into the counter using a non-leap-year modulus (365 instead of 366), producing an off-by-one wrap into 01/03/yyyy for blocks compiled after midnight and a stale token for blocks compiled earlier in the day. The CPU receives the project with valid code but the engineering station then compares the wrong checksum pair on every subsequent Go‑online and concludes that every block has drifted.

The same buggy token is propagated into the upload routine, which is why the Upload from device command does not simply report "no differences" but terminates the TIA Portal process entirely.

Because the token is generated from the engineering PC date, not from the CPU clock, the CPU itself remains healthy and continues to execute logic correctly. The CPU is online-capable, the program runs, the diagnostic buffer is intact, and tag monitoring in run mode works. The defect is purely in the offline/online bookkeeping layer of TIA Portal V11 SP2.

Reproduction Procedure

The defect is deterministic. To reproduce, follow these steps on any engineering station with TIA Portal V11 SP2 installed:

1. Close TIA Portal completely.
2. Open Windows Date and Time settings and disable automatic time synchronization with the Internet time server.
3. Manually set the date to 29 February of any leap year (for example, 2012, 2016, 2020, or 2024). Do not modify the time.
4. Launch TIA Portal V11 SP2 and open any S7-1200 project. Use an existing project or create a new one with the CPU 1214C.
5. Compile the project (Project > Compile all) and download it to the CPU.
6. Click Go online. Every block shows the "modified in offline" indicator even though the offline copy is the one that was just downloaded.
7. Run Online > Compare offline/online. The compare editor reports "No differences" for every block.
8. Click Online > Upload from device. TIA Portal becomes non-responsive and Windows displays the program-hang dialog.

Immediate Workaround

The workaround is a single PC-side change that takes effect immediately and does not require modifying the project, the CPU firmware, or the TIA Portal installation. Apply it before doing any further downloads, uploads, or online comparisons.

1. Save the project in TIA Portal and close TIA Portal.
2. Open Windows Date and Time and set the date to any value that is not 29 February. 28 February or 1 March of the same year both work.
3. Re-enable Internet time synchronization or re-apply the corporate NTP policy.
4. Restart TIA Portal V11 SP2 and reopen the project.
5. Compile the project and download it to the CPU. The offline/online indicator clears for every block.
6. Run Online > Compare offline/online to confirm "No differences" is reported.
7. Run Online > Upload from device to confirm the upload completes without crashing TIA Portal.

Permanent Resolution

The workaround restores functionality, but the only true fixes are to remove TIA Portal V11 SP2 or to upgrade the S7-1200 firmware to a release whose reconciliation routine accepts the corrected token. Choose one of the following paths:

Firmware upgrades for the S7-1200 are distributed by Siemens through the Siemens SiePortal. Always match the firmware file to the exact order number (MLFB) printed on the front of the CPU. The CPU 1214C AC/DC/Relay ships under MLFB 6ES7214-1BG40-0XB0 (FW 4.x) and the older FW 2.2 variants under 6ES7214-1AE30-0XB0. Consult the S7-1200 system manual for the firmware update procedure.

Verification Procedure

After applying the workaround or permanent fix, perform the following verification sequence. Every step must pass before the project is released to production.

1. Confirm the PC date is not 29 February and that NTP is enabled.
2. Open the project in TIA Portal and execute Project > Compile all. Compile must complete with zero errors.
3. Connect to the CPU and execute Online > Go online. The status bar must show "Online" without the modified-indicator overlay on any block.
4. Execute Online > Compare offline/online. The result pane must report "No differences" for every block.
5. Execute Online > Upload from device. The upload must complete; a "Differences found" dialog is acceptable as long as TIA Portal does not crash. Accept the upload if the offline project is to be replaced by the in-CPU version.
6. Open Online & Diagnostics > Diagnostic buffer. Confirm that no entries with event ID 0x13FE or 0x35E1 related to firmware mismatch or checksum are present.
7. Add a single no-op change to OB1 (for example a comment), recompile, and download. Confirm that only the changed block shows the modified indicator and that all other blocks remain "identical".
8. Power-cycle the CPU and re-attempt Go online. The online connection must succeed within 5 seconds and the modified indicators must remain correct.

Data Integrity and Recovery

Despite the alarming crash of the upload routine, the program inside the CPU remains intact and continues to execute. The following data hygiene steps protect the project archive during the recovery phase:

• Before any corrective action, archive the entire project folder (TIA Portal projects are file-based and can be zipped). Retain the original V11 SP2 archive plus a dated backup of every edit.
• If the upload dialog shows differences after the workaround is applied, choose Upload to programming device only after confirming the offline project has not yet been edited. Upload then merges the CPU runtime view into the offline project.
• If the upload continues to crash even after the date change, terminate TIA Portal via Task Manager, delete the local *.hmi and *.tmp caches in the project working directory, and reopen the project. Recompile before any further online operation.
• For permanent migration to TIA Portal V13 or later, use the Migrate project wizard rather than manual block export/import. Migration preserves the symbolic references, the HMI tag connections, and the hardware configuration including the PROFINET device names.

Related Defects and Cross-Platform Notes

The 29 February date bug is the highest-profile defect in the TIA V11 generation, but engineers commissioning S7-1200 CPUs on this stack should be aware of three related issues that surface under similar conditions:

The "Not compatible" message is documented in the Siemens SiePortal knowledge base for CPU 1214C FW V3.0.2 paired with TIA V11. The canonical reference is the S7-1200 system manual and the SIMATIC Automation Tool help, both distributed through the Siemens SiePortal.

Best Practices for Future Leap-Year Commissions

1. Lock the engineering PC date to NTP. Disable manual date adjustment on every engineering laptop. A controlled date prevents the 29 February token from ever being written into a project file.
2. Migrate off TIA Portal V11 SP2. V11 reached end of life in 2014. Migrate all active projects to TIA Portal V15.1 or later, which includes long-term support and a corrected reconciliation engine.
3. Pin firmware versions in source control. Tag the project archive with the exact TIA Portal version and the CPU firmware version. Date-related defects are far easier to diagnose when the engineering stack is reproducible.
4. Document the leap-day test. For every S7-1200 firmware and TIA Portal combination that is in production, run a one-day regression test on 29 February (or with the PC clock temporarily set to that date) before the calendar reaches the next leap year.
5. Maintain a SIMATIC Memory Card image. For critical machines, store a transfer card image of the project so that the CPU can be restored in minutes if a future date-related defect ever renders the live image inconsistent.

Field Commissioning Checklist

Use the following checklist during the kickoff of every S7-1200 project built with TIA Portal V11 SP2, regardless of whether the current calendar date is a leap day.

• Engineering PC date: not 29 February, NTP enabled.
• TIA Portal version: V11 SP2 confirmed; TIA V12 or later installed on at least one secondary laptop for migration testing.
• CPU order number (MLFB): matches the hardware configuration in the project (for example, 6ES7214-1BG40-0XB0).
• CPU firmware: V2.2 - V3.0.2 confirmed; note in the project archive whether a V4.x upgrade is planned.
• PG/PC interface: TCP/IP Auto, accessible nodes scan returns exactly one S7-1200 CPU.
• First download: clears the "modified" indicator on every block.
• Round-trip: edit, recompile, download, online compare = "No differences".
• Upload: completes without crashing TIA Portal.
• Diagnostic buffer: no event IDs 0x13FE, 0x35E1, or 0x4300 after first download.
• Archive: zipped project backup with date, TIA version, and CPU firmware annotated.