Siemens S7-1200 Firmware Update: TIA Portal Compatibility Guide

Overview

The SIMATIC S7-1200 CPU stores its operating firmware in onboard flash memory. Unlike a program, the firmware is the internal execution engine that defines the instruction set, web server features, motion capabilities, and CPU-internal diagnostics. A change in firmware version is therefore not a user operation but a controlled maintenance task that must match the engineering tool selected in the project.

When a CPU is delivered from the factory it typically carries a baseline firmware version (commonly V1.0 on the early 121x and 122x/123x/124x/150x hardware variants) or a higher factory version such as V2.0 or V4.x. Loading a project that was created with a TIA Portal selecting a different firmware version causes the engineering tool to flag an inconsistency. Resolving that mismatch requires either selecting the correct CPU/firmware in the project or updating the physical CPU firmware so it matches the project target.

Siemens provides two official paths for changing S7-1200 firmware: an online update from the connected PG/PC using the Online & Diagnostic tools in TIA Portal, and an offline update using a SIMATIC Memory Card (SD card) prepared with the firmware update package. Both methods are documented in the official Updating firmware section of the S7-1200 manual collection.

TIA Portal and Firmware Compatibility Matrix

The interaction between the TIA Portal version, the firmware version selected in the device configuration, and the actual firmware on the physical CPU follows a fixed compatibility rule: the project configuration and the target CPU must be aligned, and the TIA Portal must be new enough to know the firmware descriptor in question.

This matrix is the root cause of the most common S7-1200 firmware complaint: a V2.0 CPU is shipped from Siemens, the educational software bundle (STEP 7 V10.5 SP1) only contains a V1.0 device descriptor, the user loads the project, and the engineering tool rewrites or coerces the CPU into a V1.0-compatible state. The PLC is not damaged, but the V2.0 capabilities (such as the integrated web server and the optimized block access) become inaccessible until firmware V2.0 is restored.

Firmware Version Feature Differences

Each major firmware release on the S7-1200 introduces or unlocks features that are otherwise latent in the hardware. The following table summarizes the version-to-version deltas most relevant to commissioning and support decisions.

When a CPU is downgraded to V1.0 (intentionally or by a mismatched project download), the V2.0 feature block is masked, not deleted. Restoring V2.0 or higher firmware re-enables those features without any hardware change.

Prerequisites for Firmware Update

1. Identify the exact CPU order number (MLFB). The firmware package is bound to the article number, e.g. 6ES7214-1BE30-0XB0 for CPU 1214C AC/DC/Rly. Mixing order numbers results in a failed update and a CPU in STOP.
2. Match TIA Portal version to target firmware. Use the Siemens Support Online HSP (Hardware Support Package) mechanism to teach older TIA Portal versions the newer firmware descriptor. New firmware is supported in the matching TIA Portal release or later, never in an earlier release.
3. Provide stable 24 V supply to the CPU. Loss of supply during a flash write can brick the CPU. Use a UPS or buffer the supply for the duration of the update (typically 1 to 3 minutes for S7-1200).
4. Stop the CPU before initiating the firmware update. A running CPU will be placed into STOP by the update routine, but a clean stop prevents scan-time faults from corrupting the log.
5. For SD card method: Use a Siemens-branded SIMATIC Memory Card (SMC) of at least 4 MB; the 24 MB card referenced in legacy kits is functionally identical to modern 4 MB / 12 MB / 24 MB / 256 MB / 2 GB cards for the S7-1200 update use case.
6. Have a serial or project backup of the current user program. Firmware updates preserve the user program on the CPU but a project backup on the engineering PG is mandatory engineering practice.

Online Firmware Update via TIA Portal

The online path is the preferred method for a single CPU that is reachable on the PROFINET/PROFIBUS network and physically accessible to confirm a successful restart. The procedure is documented in the Updating firmware page of the TIA Portal cloud manual.

1. In the project tree, select the S7-1200 CPU and open Online & Diagnostics from the context menu.
2. Expand the Functions folder and select Firmware Update.
3. In the right pane, TIA Portal displays the currently connected CPU's article number, the firmware version installed, and the firmware files available on the local PG.
4. Click Browse and navigate to the firmware update package (typically a .upd file extracted from the HSP download). The path looks similar to C:\Program Files\Siemens\Automation\HWUpdate\6ES7214-1BE30-0XB0\FW_UPDATE\V04.07.00.
5. Select the target firmware version and click Execute Update. The CPU enters STOP, the MRES LED pattern indicates a flash operation, and the CPU automatically restarts when the update completes.
6. After the restart, re-compare the online and offline configuration. The online diagnostic should now report the new firmware version under Diagnostics > Device Information.

Firmware Update via SIMATIC Memory Card (Offline)

The SD card method is the field-engineer fallback when the CPU is not online-reachable, when the TIA Portal on site is older than the target firmware, or when an entire fleet of CPUs (for example, an educational kit of 6 CPUs) must be brought to a common baseline.

1. Insert the SMC into a card reader on the engineering PC.
2. Create the folder structure required by the S7-1200 update: place the firmware .upd file and the S7_JOB.S7S trigger file at the root of the card. The trigger file content is plain text and is generated by selecting PLC > Memory Card File Browser > Firmware Update in TIA Portal, or manually written as:

   // S7_JOB.S7S
   Firmware_Update

3. Safely eject the SMC and power down the target CPU.
4. Insert the SMC into the CPU's card slot.
5. Power on the CPU. The RUN/STOP, MAINT, and ERROR LEDs cycle to indicate a firmware read; the CPU copies the firmware from the card into internal flash, then performs an automatic restart.
6. After the restart, remove the SMC. The card is no longer required for normal operation.

Firmware Downgrade Considerations

Downgrading firmware on the S7-1200 is technically supported by Siemens only when moving to a version that the TIA Portal descriptor knows. Practical cases that drive a downgrade request include:

• Reclaiming V1.0 behavior on a V2.0 CPU to match an existing V10.5 project archive that cannot be re-engineered.
• Reversing a misapplied firmware push from a mismatched project download.
• Replicating a test environment that runs at a known firmware level for reproduction of a support case.

The mechanics of a downgrade are identical to an upgrade (online or SD card), only the source and target versions change. Note that features introduced after the target version (for example, OPC UA on V4.x) are no longer available after the downgrade, but the user program in the CPU is preserved.

Educational Kit Specifics

Siemens has historically sold educational kits containing 6 × CPU 1214C AC/DC/Rly (order number 6ES7214-1BE30-0XB0) bundled with STEP 7 V10.5 SP1 on six DVDs. The factory firmware on these CPUs at the time of the kit was V2.0, but V10.5 SP1 only supports V1.0 device descriptors. The result is that an end-user running the bundled software against the V2.0 CPU will see the project compile and download as a V1.0 configuration, masking the V2.0 web server and optimized block access features.

For institutions in this situation, the supported recovery path is:

1. Upgrade the engineering tool to TIA Portal V13 or later (free for educational licensees through the Siemens Automation & Drives educational program).
2. Install the matching HSP for the desired firmware level (V2.0, V4.0, V4.4, V4.6, or V4.7).
3. Perform an online firmware update or an SD card update to bring the CPU firmware to match the project.

Contacting the local Siemens field office for a firmware-update visit is the recommended path when six or more CPUs are involved; Siemens field representatives can perform the updates in a single session using a card writer and pre-loaded firmware.

Verification and Diagnostics

After any firmware change, verify the new state using the following checks:

1. Online > Online & Diagnostics > Diagnostics > Device Information: confirm the firmware version reported by the CPU matches the project target.
2. Project > Compile > Software (rebuild all): a clean compile after the firmware change verifies that no block attributes rely on features that have moved or been renamed between versions.
3. Web server test: navigate to http://<cpu-ip>/ from a browser. A V2.0+ CPU will expose the user-defined web pages; a V1.0 CPU only shows the diagnostic default page.
4. Diagnostic buffer read: in Online & Diagnostics, open Diagnostics Buffer. A clean firmware update leaves an event of category "Firmware update successful" with the old and new version strings. Any error events here point to a partial flash and require a repeat of the procedure.
5. PROFINET device name and IP: firmware updates do not change the IP address or PROFINET device name on the CPU, but a power-cycle is recommended to confirm network reattachment.

Troubleshooting Matrix

Field-Commissioning Checklist

• Confirm the CPU MLFB and the firmware version printed on the front of the CPU against the project target.
• Verify the TIA Portal version installed on the PG supports the target firmware descriptor; otherwise install the matching HSP.
• Capture a project backup (.ap14, .ap15, .ap16, or .ap17 depending on TIA Portal version) before any firmware operation.
• Document the old and new firmware versions in the commissioning log; this is mandatory for support case escalation.
• For fleet updates, label each SMC with the target CPU MLFB and firmware version to avoid cross-application errors.
• After the update, perform a STOP-to-RUN transition under no load and observe the diagnostic buffer for one scan cycle before reconnecting field wiring to actuators.

Frequently Asked Questions