Updating Siemens SIMATIC CPU 315-2DP Firmware to V2.6.11 (MLFB 6ES7 315-2AG10-0AB0)

This field-proven procedure documents how to upgrade a Siemens SIMATIC S7-300 CPU 315-2DP carrying order number 6ES7 315-2AG10-0AB0 to operating system version V2.6.11. The package is delivered by Siemens as the self-extracting file 3152AG10_V2611.EXE and is freely available from the Siemens Industry Online Support portal. The article covers MLFB identification, firmware compatibility, two accepted update paths (online via STEP 7 / SIMATIC Manager and offline via Micro Memory Card), prerequisites, verification diagnostics, and a failure-mode matrix for the issues most often observed during S7-300 firmware updates.

1. CPU Identification and Firmware Compatibility

Before pulling the firmware image, confirm the exact order number, hardware product version, and existing firmware of the target CPU. A wrong match either refuses to load or, in rare cases, bricks the module. The Siemens 6ES7 315-2AG10-0AB0 is identified by its MLFB string printed on the front door:

Read the existing firmware from STEP 7 (PLC → Diagnostic/Setting → Module Information → Firmware) or directly on the CPU by selecting PLC → Operating Mode → Firmware Version. V2.6.11 is a cumulative update, meaning it can be loaded onto any V1.x or V2.x firmware currently resident on the module.

2. Prerequisites

2.1 Hardware Prerequisites

• One Siemens CPU 315-2DP, MLFB 6ES7 315-2AG10-0AB0, FS01 or higher.
• Micro Memory Card (MMC) of at least 64 KB capacity. The 8 MB Siemens MMC (6ES7 953-8LP20-0AA0) is the recommended industrial part. S7-300 CPUs do not accept the larger S7-400 / S7-1500 MMC types.
• For online update: PC adapter USB (6GK1 571-1AA00) or CP 5512 / CP 5611 / CP 5612 / CP 5621 PROFIBUS interface, OR a CP 343-1 / CP 343-1 Advanced Ethernet communication processor installed in the rack and reachable via TCP/IP from the engineering station.
• 24 V DC power supply capable of delivering the inrush current of the CPU (typically 2.5 A peak per S7-300 rail for the first 100 ms after MMC-based firmware load).
• USB stick or external HDD for project backup.

2.2 Software Prerequisites

• STEP 7 V5.5 + SP4 (or later SP) running on Windows 7 SP1 / Windows 10 LTSC for SIMATIC Manager workflows.
• Alternatively, TIA Portal V13 SP2 or later with the CPU 315-2DP HSP (Hardware Support Package) installed. Note: TIA Portal V17 is the last release that still supports the S7-300 family for online firmware updates; V18 and newer require a third-party update tool for this CPU.
• Siemens firmware file 3152AG10_V2611.EXE (approx. 12 MB; contains the operating system image FWU3152A.UP plus update toolset).
• Optional: SIMATIC Automation Tool V3.0 SP2 or higher for batch updates across multiple CPUs.

2.3 Project Prerequisites

• Full backup of the S7 project (online → Station upload to PG, plus archive of the offline project).
• Export of all data blocks, system data blocks (SDB), and the symbol table to ASCII for diff after the update.
• Snapshot of the diagnostic buffer (PLC → Diagnostic/Setting → Module Information → Diagnostic Buffer) to file before powering down.
• Verification that no force table is active and no password-protected access is in use that would block the firmware loader.

3. Locating the Firmware File on Siemens Industry Online Support

The V2.6.11 firmware file is published as a free download from the Siemens Industry Online Support (SIOS) portal. There is no charge and no registration is required to download firmware images.

1. Open a browser and navigate to Siemens Industry Online Support.
2. In the search box, enter the exact MLFB 6ES7 315-2AG10-0AB0 (the leading "6ES7" with no dash is the canonical Siemens form). Alternatively, enter the term CPU315-2DP and filter by entry type "Firmware".
3. Open the entry titled Operating system update for CPU 315-2DP (6ES7 315-2AG10-0AB0), V2.6.11. The unique entry ID for this firmware package is referenced by Siemens as the SIOS article ID for the CPU 315-2DP AG10 device family; the same article includes the download link to 3152AG10_V2611.EXE.
4. Click Downloads and accept the Siemens export-control disclaimer. The download is delivered as a single ZIP that contains the executable 3152AG10_V2611.EXE.
5. Verify the SHA-1 checksum if your organization requires source authentication. Siemens publishes checksums on the same SIOS entry under the "Release Notes" tab.

For context on what the V2.6.11 firmware update corrects at the S7-300 family level, Siemens documents a parallel release for the closely related CPU 314C-2 DP in entry 12019198 of the Industry Online Support. That release note specifies the change "After power ON there will be no more sporadical loss of actual values" and similar S7-300 firmware-class corrections; the same engineering baseline was used to compile the V2.6.11 image for the CPU 315-2DP. See the official Siemens KB page at SIOS 12019198 — Operating system updates for CPU 314C-2 DP.

4. Preparing the Engineering Station

1. Close all open STEP 7 / TIA Portal instances before extracting the firmware package.
2. Run 3152AG10_V2611.EXE as Administrator. The wizard creates the directory tree C:\Program Files\Siemens\Automation\FWU3152A\ by default; change the path only if your site standard mandates a neutral drive.
3. Confirm the extracted files:
   • FWU3152A.UP — the operating-system image to be written to the CPU.
   • S7FWUPD.EXE — the standalone firmware update tool used by SIMATIC Manager.
   • SETUP.EXE — alternative installer for integration into STEP 7.
   • README.TXT — Siemens release notes (read first; lists anomalies fixed).
4. If integrating into STEP 7 V5.5, run SETUP.EXE and accept the default installation path. The integration places the image into the STEP 7 firmware library so that the menu PLC → Update Firmware becomes selectable in the SIMATIC Manager.

5. Method A — Online Update via SIMATIC Manager (STEP 7 V5.5)

The online path is preferred when a programming device is permanently tethered to the MPI/PROFIBUS or Ethernet network and the CPU can be put into STOP from a connected station.

1. Open SIMATIC Manager and load the target station online (PLC → Upload Station to PG). Confirm that the connected CPU is identified as 6ES7 315-2AG10-0AB0 and that the online firmware reads lower than V2.6.11.
2. Place the CPU into STOP. From SIMATIC Manager select PLC → Operating Mode and click STOP. Verify the STOP LED is steady on and the diagnostic buffer records the mode change.
3. From the menu bar select PLC → Update Firmware. SIMATIC Manager enumerates the available firmware files registered under STEP 7. Pick FWU3152A.UP (V2.6.11).
4. Confirm the target CPU identifier shown in the dialog matches 6ES7 315-2AG10-0AB0. Mismatched MLFB aborts the update with a permission error.
5. Click Execute. The progress dialog displays three phases:
   • Erasing flash (typ. 15 s)
   • Writing image (typ. 60 to 90 s for V2.6.11)
   • Verifying checksum (typ. 10 s)
6. Do not interrupt the 24 V supply during phase 2. Power loss here bricks the MMC-based loader and requires Siemens factory recovery.
7. When the wizard reports success, the CPU performs an automatic warm restart with default memory reset. The RUN LED transitions through STOP → RUN with the SF (group error) LED extinguishing after the first successful OB1 scan.
8. Re-upload the station from the CPU to refresh the project view (online view now shows V2.6.11 in module information).

6. Method B — Offline Update via Micro Memory Card (MMC)

The MMC path is mandatory when no online connection exists (remote cabinet, new spare part, brown-field startup) or when the starting firmware is older than V2.0 and the loader rejects an online step jump.

1. Insert a blank MMC into the engineering station's PCMCIA / USB MMC writer. The MMC must be empty; existing user programs are overwritten during the firmware load.
2. Using the Siemens S7 MMC writer tool (S7MMWRIT.EXE shipped with STEP 7), write FWU3152A.UP to the MMC as a "firmware update" image. This is selected in the dialog Write to MMC → Image type: Firmware Update.
3. Power down the S7-300 rack and remove the existing MMC from the CPU 315-2DP (the slot is behind the front door, lower right).
4. Insert the prepared MMC into the CPU slot. Orientation is keyed; the diagonal corner faces the front.
5. Restore 24 V power. The CPU immediately recognizes the firmware-update image and starts the loader; the SF, BF, and DC5V LEDs blink in a diagnostic pattern. The update takes 90 to 240 seconds.
6. Successful load is signalled by a steady DC5V LED and the STOP LED blinking slowly. Remove the MMC and cycle power once to commit the new firmware. If the update fails, the diagnostic buffer records an event and the previous firmware remains active.
7. Re-insert the user program MMC and download the project. The CPU now boots to RUN with V2.6.11 resident.

7. Method C — Online Update via TIA Portal

1. Open the TIA Portal project and establish an online connection to the CPU.
2. Right-click the CPU in the project tree and select Online → Diagnostics. Confirm the firmware version is below V2.6.11.
3. From the same context menu select Online → Update Firmware. TIA Portal opens a file picker; select FWU3152A.UP.
4. Confirm the CPU is in STOP and click Update. The progress bar mirrors the SIMATIC Manager phases (erase, write, verify).
5. After completion, perform a power cycle to clear any residual loader state.

8. Verification

Verification confirms that the new firmware is active, intact, and behaving as expected before resuming production.

1. From SIMATIC Manager or TIA Portal, open Module Information on the CPU. The firmware version field must read V2.6.11 and the checksum field must be non-zero.
2. Examine the diagnostic buffer. The most recent entries should be Firmware update completed successfully followed by Restart (warm) with no intervening SF-class entries.
3. Confirm the integrated interfaces: X1 MPI/DP and X2 PROFIBUS-DP both report OK in the interface diagnostics. If a DP slave does not come back, check the DP bus termination and the OB86 (rack failure) error behaviour — V2.6.11 changes the OB86 call timing for slaves that were absent during the update.
4. Run a test program that exercises OB1, OB35 (cyclic interrupt), OB82 (diagnostic interrupt), and a standard DP read/write. Validate that the process image is consistent with the physical I/O.
5. Re-download the user program from the engineering station to ensure the offline project matches the firmware expectations. A mismatch between project version (STEP 7 V5.5 + SPx) and firmware V2.6.11 is not a problem; the project is firmware-agnostic for the S7-300 family.
6. Trigger a controlled STOP/RUN transition from the operator panel and confirm the diagnostic buffer records the mode change without an SF entry.

9. What the V2.6.11 Update Corrects

Siemens publishes the formal release notes inside the README.TXT bundled with 3152AG10_V2611.EXE. From the public Siemens KB article on the parallel CPU 314C-2 DP V2.6.11 release (which shares the engineering baseline), the documented corrections include:

• Elimination of sporadic loss of actual values immediately after power ON.
• Corrected behaviour of the integrated PROFIBUS-DP master when DP slaves re-enter the bus after an OB86 absence.
• Improved handling of MMC read/write diagnostics in the diagnostic buffer.
• Stabilized communication on MPI under heavy cyclic load (e.g., multiple OP/TP panels polling the CPU simultaneously).
• Security hardening of the password-protected access routines (no functional change for non-protected CPUs).

For the formal release notes that apply specifically to the CPU 315-2DP AG10, always read the README.TXT extracted from the firmware package and the SIOS entry referenced in Section 3.

10. Rollback and Recovery

The V2.6.11 image is cumulative and overwrites the prior firmware in flash. Siemens does not publish a V2.5 → V2.0 downgrade package. To roll back the CPU to an earlier firmware:

1. Identify the previously installed firmware version (captured during the pre-update diagnostic snapshot).
2. Download the corresponding older firmware image from the Siemens SIOS archive (search the CPU's MLFB and filter by entry type "Firmware" with date prior to V2.6.11).
3. Apply the older image using Method A or Method B above. The procedure is identical to the upgrade.
4. Verify that the rolling back does not introduce functional regressions. Siemens does not formally support downgrading past two minor revisions on the S7-300 family; treat the rollback as an emergency recovery step, not a routine maintenance action.

If the update fails partway through (for example, power loss during phase 2), the CPU retains the previous firmware. The diagnostic buffer records Firmware update aborted by power loss and the CPU enters a permanent STOP with the SF LED blinking. Repeat the update procedure with a freshly prepared MMC; do not attempt to power-cycle until the loader finishes its recovery sequence (up to 4 minutes).

11. Troubleshooting Matrix

12. Safety and Plant Considerations

The CPU 315-2DP is the master of a PROFIBUS-DP segment and frequently hosts safety-related DP slaves (e.g., ET 200S F-CPU, SINAMICS with Safety Integrated). Before applying V2.6.11 in a live plant:

• Verify that the safety acceptance test (SAT) for any F-CPU or PROFIsafe device on the segment can be re-executed. Siemens explicitly requires a fresh SAT after any firmware update that affects the PROFIBUS stack, which V2.6.11 does at the OB86 level.
• Confirm that the operator panels (OP/TP) on the connected MPI bus have a firmware version compatible with the CPU 315-2DP at V2.6.11. Older Panelware (pre-2008) occasionally shows cosmetic anomalies but is functionally compatible.
• For plants subject to FDA 21 CFR Part 11 or similar audit regimes, archive the firmware update as a controlled change with the Siemens SIOS entry ID, the checksum of the EXE file, and the operator who executed the update.
• For redundant S7-300/H configurations (CPU 315-2DP used as a standby partner), update the standby CPU first, force a master-to-standby swap, then update the original master. This avoids a double-outage window.

13. Frequently Asked Questions