S7-1200 CPU Firmware Update: V1.0 to V2.2 via SIMATIC Memory Card

Overview

The first-generation SIMATIC S7-1200 CPU (order numbers 6ES721x-1xx30-0XB0) is factory-shipped with firmware V1.0 on the older hardware revisions and supports a maximum firmware release of V2.2. The V2.2 image is the final feature release for this hardware; V3.x and V4.x firmware images will not load and require the second-generation (6ES721x-1xx40-0XB0) or third-generation (6ES721x-1xx50-0XB0) CPUs respectively. The only sanctioned method to install the V2.2 update on an existing V1.0 CPU is a memory-card-based firmware update using a SIMATIC MC 24 MB SD card. Online firmware download via TIA Portal is not available for the first-generation S7-1200.

This article documents the complete procedure: identifying the CPU generation, preparing the SIMATIC memory card, executing the update, verifying the result, and migrating the TIA Portal project from V11 to V14 while retaining the existing user program.

Prerequisites

Before starting, confirm the following items are available:

• SIMATIC S7-1200 CPU, first-generation, currently running firmware V1.0 or V1.x (check via Online > Accessible Devices in TIA Portal or via the CPU display for CPUs that include one).
• SIMATIC Memory Card, 24 MB (6ES7954-8LF02-0AA0) or 256 MB / 2 GB / 32 GB equivalent (6ES7954-8LL02-0AA0 / 6ES7954-8LP02-0AA0 / 6ES7954-8LT02-0AA0). Only Siemens-branded SIMATIC SD cards are supported for the firmware-update workflow; consumer-grade SD cards fail the PLC's card validation and may produce a SF (system fault) on insertion.
• The firmware update file (.upd) matching the exact MLFB and firmware version. For V2.2 of CPU 1214C DC/DC/DC the file is typically 6ES7214-1AE30-0XB0_V22.UP D; the file naming always follows <MLFB>_V<XX>.UPD.
• PC with SD card reader/writer and Windows file system access (FAT16/FAT32, the same file system the card is shipped with).
• 24 V DC power supply rated for the CPU under load; a supply sag during the update will brick the device and require return-to-factory.
• TIA Portal V11 SPx or TIA Portal V14 (or newer) installed, depending on the target project.

Identifying the CPU Generation and Maximum Firmware

Before attempting any update, physically inspect the front of the CPU and read the order number (MLFB). The first four characters of the firmware-relevant block identify the platform:

Open TIA Portal > Project Tree > Devices & Networks, select the CPU, and read the Device View > Properties > General > Order Number and the existing Firmware Version under Online & Diagnostics > Diagnostics. The PLC's onboard web server (only enabled on CPUs at V2.0 and higher) and the CPU display on 1215C/1217C also report the active firmware revision.

Firmware File Acquisition

Obtain the .upd file from a Siemens Industry Online Support entry that matches the exact MLFB. The procedure:

1. Open the Siemens Industry Online Support entry for the specific CPU MLFB.
2. Navigate to Support > Software Downloads > Firmware updates.
3. Download the Firmware Update V2.2 for ... ZIP archive.
4. Extract the archive; the .UPD file is the only file required for the memory-card workflow.

Verify the SHA-256 hash of the downloaded .UPD against the value published on the Siemens support page. Do not transfer the file via FTP in ASCII mode; use binary transfer. Renaming the .UPD extension or placing the file in a subfolder breaks the PLC's bootloader file-system scan.

Memory Card Preparation

The firmware update is triggered by the presence of a specific folder and S7_JOB.S7S file at the card's root. A clean card needs nothing more than the firmware file, but reused cards must be sanitized.

Clean card (new or freshly formatted)

1. Insert the SIMATIC MC into the PC's SD reader.
2. Open Windows Explorer and verify the card is formatted as FAT16 or FAT32 (Siemens pre-formats the card accordingly).
3. Copy the <MLFB>_V22.UPD file directly to the root of the card.
4. Eject the card safely through Windows.

Reused card (contains a user program or earlier firmware update)

1. Insert the SIMATIC MC into the PC's SD reader.
2. Open Windows Explorer. Do not use the TIA Portal card viewer for the cleanup; the files are hidden and read-only by design.
3. Enable View > Hidden items in Explorer.
4. Delete S7_JOB.S7S at the card root.
5. Delete every folder with an .S7S extension. The PLC writes three possible folders: SIMATIC.S7S (user program), FWUPDATE.S7S (firmware payload directory), and SIMATIC.HMI (recipe/archive data on supported HMI companions). All must be removed so the bootloader re-evaluates the card from scratch.
6. Copy the <MLFB>_V22.UPD file to the root of the now-empty card.
7. Eject the card safely.

Step-by-Step Update Procedure

1. Power down the S7-1200 CPU. Maintain 24 V DC to the power supply; the PLC is to remain unpowered (CPU switch or terminal L/M off).
2. Remove any existing SIMATIC MC from the CPU's card slot.
3. Insert the prepared SIMATIC MC containing the V2.2 .UPD file into the CPU's card slot. The card is keyed; do not force it.
4. Power up the CPU. The CPU enters firmware-update mode automatically. The MAINT LED flashes yellow/green and the RUN/STOP LEDs cycle as the bootloader erases flash, writes the new image, and verifies it. The process takes 30 to 120 seconds for a 24 MB card, depending on CPU type.
5. Wait for the update to complete. When the CPU reboots, the MAINT LED is OFF, the STOP LED is solid yellow, and the RUN LED remains OFF (the CPU stops after a firmware change because the user program is cleared).
6. Remove the SIMATIC MC if you intend to reload the user program. If the card contains SIMATIC.S7S with a project, leave the card inserted and the CPU will transfer the program automatically after a power cycle.

LED Status Indicators During Update

Interpret the front-panel LEDs as follows during the procedure:

Verification

1. Establish an online connection from TIA Portal: Online > Accessible Devices > S7-1200 station.
2. Open Online & Diagnostics > Diagnostics > Diagnostics Status. Confirm the reported firmware is V2.2.
3. Open Online & Diagnostics > Diagnostics > Diagnostics Buffer. Clear the buffer and power-cycle the CPU. A clean V2.2 boot produces only the entries Startup and Restart (cold); any pre-existing I/O module complaints are diagnostic events with Event ID 0x4E4x series and may be acknowledged and ignored if the affected module is not in use.
4. Re-download the TIA V11 or V14 project. The CPU will go to RUN.

Project Migration: TIA Portal V11 to V14

The firmware update is independent of the TIA Portal project version. The recommended sequence to keep the field device and the engineering environment in sync:

1. Open the existing .ap11 project in TIA Portal V11.
2. Compile the project to confirm it is error-free. TIA V11 only supports CPU firmware V1.0 / V2.0 device descriptions; opening in V14 with the same device family upgrades the device description to V2.2 automatically during Project > Migrate project.
3. Save a backup of the V11 project before any migration. TIA migration is one-way; downgrade is not possible.
4. Open the project in TIA Portal V14 (or V14 SP1, V15, V15.1, V16, V17 as appropriate). Accept the migration prompt.
5. Select the CPU in Devices & Networks; in Properties > General > Catalog Information, set the firmware version to V2.2 if the migration wizard did not pick it up automatically.
6. Recompile. Resolve any warnings about unsupported system blocks (the V2.2 firmware keeps the V1.0 instruction set intact; only block versioning flags change).
7. Download to the now-V2.2 CPU. The transfer is incremental; existing retentive data is preserved when the corresponding tags are marked as Retain in the project.

I/O Module Compatibility Notes

Firmware V2.2 of the first-generation S7-1200 CPU is fully backward-compatible with SM 1231 / SM 1232 / SM 1234 signal modules and CM 1241 communication modules produced for the 1st-generation platform. The following operational caveats are reported in the field on V2.2 systems:

• Some SM 1231 analog input modules with hardware revision < 2 produce Channel diagnostics entries with Event ID 0x0007 ("channel temporarily unavailable") on every cold start. The channel returns to service within 1 second; the diagnostic entry can be acknowledged.
• CM 1241 RS-232 / RS-485 modules at hardware revision 1 do not support 250 kbps on V2.2; the achievable maximum is 115.2 kbps. Reconfigure the port in the device configuration or downgrade to firmware V2.0 if higher rates are required.
• CSM 1277 unmanaged switch modules are unaffected by the CPU firmware revision.
• SB 1221 / SB 1223 signal board modules function identically across V1.0 through V2.2.

Troubleshooting Matrix

Safety and Operational Considerations

A firmware update is a non-reversible operation once the bootloader commits the new image to flash. Plan the work for a scheduled maintenance window with the affected machine in a safe state. If the PLC controls an E-stop circuit, a coordinated stop, or a safety-integrated process, follow the site's lockout/tagout (LOTO) procedure and verify that the controlled equipment reaches a safe condition before removing power from the field devices.

After the update, the user program is cleared. If the original V1.0 program must be preserved, archive it from the existing card (or the TIA Portal backup) before starting the firmware update. A power loss during the firmware write will leave the CPU in a non-recoverable state; in this case the CPU must be sent to a Siemens repair center for reflashing at the factory. Budget for an emergency-spare CPU if the line is critical.

Rollback Path

The V2.2 bootloader is not field-downgradable back to V1.0 or V2.0 on the same hardware. If a regression appears after the update, the only options are:

1. Restore the user program only (the firmware remains V2.2; logic-level issues are fixed in the project).
2. Replace the CPU with a new unit of the same MLFB. The replacement ships with V1.0 or V2.0 depending on manufacturing date; the firmware update workflow can be repeated on the new unit if the existing process is to be retained.
3. Migrate the application to a second-generation CPU (6ES721x-1xx40-0XB0) and the latest supported firmware to escape the V2.2 feature ceiling.

Decision Path: Update vs. Replace

Use the following logic when planning a TIA V11 to V14 migration on a 1st-generation S7-1200:

• If the existing program runs in TIA V11 today and TIA V11 will continue to be supported on the engineering PCs, keep the PLC at V1.0/V2.0. TIA V11 is compatible with V1.0 and V2.0 firmware. The TIA V14 project can be built, compiled offline, and held for a future CPU swap rather than forced onto an old platform.
• If the engineering environment must move to TIA V14 or later, upgrade the firmware to V2.2 to obtain a single, consistent device version across all online and offline views. This is the only supported way to keep the old CPU working in TIA V14.
• If the application requires V3.x or V4.x features (OPC UA, security integrated, expanded trace, new web-API methods, optimized block access on standard CPUs), replace the CPU with the corresponding second- or third-generation module. A firmware update is not possible on 1st-generation hardware.