Fix ET 200SP AI 4xRTD/TC Firmware Mismatch in TIA Portal V16

Problem Overview

The ET 200SP distributed I/O system frequently triggers diagnostic interrupts during commissioning when the AI module firmware installed in the physical module does not exactly match the version configured offline in the TIA Portal project. The most common field occurrence is on the high-feature (HF) analog input module AI 4xRTD/TC 2-/3-/4-Wire HF (article number 6ES7134-6JD00-0CA1) when wired to a S7-1200 CPU through an IM 155-6 PN ST head station.

Typical field report: a S7-1200 with an IM 155-6 PN ST head module, engineered in TIA Portal V16 with all updates installed, shows the AI 4xRTD/TC HF online with firmware V2.0.3, but the device configuration catalog only offers V1.0, V1.1, or V2.0. The PLC refuses to enter RUN and posts a configuration error referencing the analog module, but V2.0.3 cannot be selected from any drop-down, and the module refuses to downgrade to V2.0 because its factory firmware is V2.0.1 or higher. The result is a three-way lock: the physical module cannot be downgraded below V2.0.0, the TIA V16 engineering project cannot be updated to V2.0.3, and the CPU by default refuses to start with any configuration mismatch.

Affected Hardware and Software

The same incompatibility pattern is documented across the ET 200SP and ET 200AL families. The Siemens support entry "Firmware Update for ET 200SP AI 8xI 2-/4-Wire Basic" (ID 109791853) explicitly states that firmware V2.0.0 is not available for download and a downgrade of modules delivered with FS23 to firmware versions below V2.0.0 is not possible. The same restriction applies to the related ET 200AL AI 4xRTD/TC, 4xM12 (ID 110001521), where a downgrade from V2.0.x to versions below V2.0.0 is locked out. The aggregated firmware archive for all ET 200SP interface and I/O modules is published as ET 200SP Firmware Collection (ID 109804718).

Root Cause Analysis

The mismatch is not a fault in the module; it is the result of three converging constraints that must be understood before any commissioning step is taken.

1. Module firmware evolution. Siemens introduced a newer firmware (V2.0.3 in the operator's case, V2.0.x in related modules) to address functional improvements, channel-diagnostic enhancements, and bug fixes. Modules are shipped with this newer firmware on the production line; the printed "factory firmware" stamped on the module label is the V2.0.3 / V2.0.x image and is authoritative.
2. Engineering catalog lag. TIA Portal V16, even with all updates installed, does not contain a device description (HSP entry or GSD) that includes firmware V2.0.3. The catalog only offers V1.0, V1.1, and V2.0. The only way to obtain V2.0.3 support is to upgrade TIA Portal to V17 or later, or to install a newer Hardware Support Package (HSP) that adds the newer module description. The newer HSPs are aggregated in ET 200SP Firmware Collection (ID 109804718) for the I/O modules and in S7-1500 / ET 200SP CPU firmware update (ID 109478459) for the CPUs.
3. Anti-rollback protection. Starting with module functional state (FS) 03 (factory firmware V2.0.1) for the AI 4xRTD/TC HF and FS23 for the AI 8xI Basic, the firmware loader refuses any downgrade to a version earlier than V2.0.x. This is tamper protection: once a module boots with the V2.0.x bootloader, the older firmware images cannot be reflashed, even via SIMATIC Automation Tool, TIA Portal "Online & Diagnostics → Firmware Update", or the Web server method.

The result is a deadlock that the standard configuration consistency check in the S7-1200 cannot resolve on its own. The CPU must be told to tolerate the difference, or the engineering environment must be upgraded to one that knows about the newer firmware.

Diagnostic Procedure

Follow this sequence on-site to confirm the failure mode and collect the data required for the resolution decision.

1. Open the TIA Portal project and go online to the S7-1200 CPU.
2. In the project tree, expand Distributed I/O → IM 155-6 PN ST → the slot holding the AI module.
3. Right-click the AI module and select Online & Diagnostics. The diagnostics status pane reports a configuration error such as "Firmware version of the module does not match the configured version" or a PROFINET channel-diagnostic interrupt 0x001E / 0x001F.
4. In the same dialog, switch to the Firmware tab. The dialog displays the actual firmware currently running on the module (e.g., V2.0.3) and the firmware selected in the offline project (e.g., V2.0.0).
5. In the device configuration (offline), open the module properties → Module parameters and note the firmware version shown under Module identification.
6. Cross-check the module's article number and functional state. Article 6ES7134-6JD00-0CA1 with a functional state of FS03 or higher means the factory firmware is V2.0.1+, hence downgrade is not possible.
7. Read the CPU's diagnostic buffer (online → CPU → Diagnostic buffer). Look for entries of class "Configuration error" with associated module address matching the AI slot.

If the offline firmware is set higher than the online firmware, the diagnostics also report a "Module has a lower firmware version than configured" type message. If the offline firmware is set lower than V2.0.3, the message will be "Module has a higher firmware version than configured". Both are resolved with the same set of options.

Resolution Methods

There are three valid approaches, listed in order of preference. Pick Method 1 for short-term commissioning, Method 2 to clean up the diagnostic buffer, and Method 3 for a permanent supported configuration.

Method 1 – Enable "Startup CPU even if mismatch" (preferred for commissioning)

The S7-1200 CPU contains a startup-parameter checkbox that permits the controller to enter RUN even when one or more configured modules report a configuration error during startup. The module will still report a diagnostic interrupt and the SF (group fault) LED will be lit, but user program execution continues, the process image of inputs is updated, and analog values are read with full functionality.

Procedure:

1. In the TIA Portal project, open Devices & Networks and select the S7-1200 CPU.
2. Open the inspector window → Properties → General → Startup.
3. Under the Configuration error section, enable "Startup CPU even if there is a configuration error" (German: "CPU auch bei Konfigurationsfehler starten") and also enable "Permit operation with configured/actual mismatch" if available in your firmware version.
4. Save, compile, and download the hardware configuration to the CPU.
5. Cycle power to the station. The CPU should now go to RUN, and the AI module should pass startup with a soft diagnostic rather than a hard fault.

This method does not suppress the SF LED on the module or the diagnostic buffer entries, but it does allow the plant to run while a permanent solution is engineered. It is the correct choice for brownfield installations where the physical modules cannot be replaced and TIA Portal cannot be upgraded in the short term.

Method 2 – Match the offline firmware to the closest available older version (V2.0)

If the user prefers a clean diagnostic buffer, the offline firmware in the project can be set to V2.0.0 and the startup tolerance enabled to absorb the residual 0.0.3 difference. TIA Portal V16 contains the V2.0.0 device description for the AI 4xRTD/TC HF, and the S7-1200 will accept this combination if and only if "Permit operation with configured/actual mismatch" is active in the CPU startup parameters.

1. Open the device configuration for the IM 155-6 PN ST.
2. Select the AI module slot and open Properties → General → Module identification (or Catalog information).
3. Set the firmware version to V2.0.0.
4. Save and download.
5. Combine with Method 1's startup tolerance; either alone is not sufficient for the V2.0.3 → V2.0.0 delta.

Method 3 – Upgrade TIA Portal to V17 or V18 and install the matching HSP

For a permanent, supported configuration, upgrade the engineering environment. TIA Portal V17 (and later) ships with hardware support packages that contain the AI 4xRTD/TC HF V2.0.3 device description. After the upgrade:

1. Open the same project. TIA Portal will offer to migrate it.
2. Install the latest ET 200SP HSP from ET 200SP Firmware Collection (ID 109804718). This entry aggregates the current firmware images for all ET 200SP interface modules and I/O modules.
3. In the device configuration, select firmware V2.0.3 for the AI module.
4. Download the hardware configuration. The diagnostic mismatch disappears and the SF LED goes out.

Method 3 is the only option that produces a clean diagnostic buffer with no startup tolerance required.

Firmware Management and Downgrade Limits

For planning purposes, the following downgrade boundaries apply to the ET 200SP HF analog input family and the related ET 200AL analog input:

In other words, once a module leaves the factory at FW V2.0.1 or higher, the firmware loader enforces a one-way ramp: the only downgrade target is V2.0.0 (when available), and the only upgrade direction is to subsequent point releases. The user cannot reset a module to its historical V1.x line.

To perform a firmware update within the supported range, use one of:

• TIA Portal → Online & Diagnostics → Firmware Update (works for S7-1200 controllers but limited to the FW images bundled with the active HSP).
• SIMATIC Automation Tool, with the FW file from ET 200SP Firmware Collection (ID 109804718).
• PRONETA for PROFINET devices, useful for diagnostic and pre-commissioning FW checks.

Configuration Steps (Detailed Walkthrough)

This is the recommended TIA Portal V16 procedure to bring the station to RUN with the V2.0.3 module on the V16 engineering base.

1. In the project tree, open Devices & Networks and select the S7-1200 CPU.
2. Open the inspector window → Properties → General → Startup (German: "Startup").
3. Check the box "CPU auch bei Konfigurationsfehler starten" / "Startup CPU even if configuration differs from actual".
4. Navigate to the IM 155-6 PN ST head module and open its device configuration.
5. Select the AI 4xRTD/TC HF slot. Open Properties → General and confirm the article number is 6ES7134-6JD00-0CA1.
6. In the firmware selector, choose V2.0.0. The drop-down will not contain V2.0.3.
7. Compile the hardware configuration (Project → Compile → Hardware (rebuild)).
8. Download to the S7-1200 CPU (Target system → Download to device → Hardware and software).
9. Power-cycle the ET 200SP station. The CPU enters RUN; the AI module reports a configuration error (SF LED red) but the analog process image is updated.
10. Read a known analog input (e.g., a Pt100 sensor on channel 0) and confirm the engineering unit value is sensible in the watch table or HMI.

If the station still does not start, the next step is to enable "Compare with actual configuration" and the "Accept compatible differences" tolerance in the same Startup property page. This is the second-level tolerance that allows the CPU to swallow any module-level catalog difference.

Verification

After applying Method 1 + Method 2, verify with the following checks:

• CPU diagnostic buffer: The entries should be informational rather than fault-level. Look for events of class Configuration rather than Error. A persistent "Module does not match configuration" entry is acceptable as long as the CPU remains in RUN and the module is exchanging I/O data.
• Module LEDs: The SF LED on the AI module will likely remain lit or flash red; the green PWR and channel-active LEDs should behave normally. If both the SF and BF LEDs are off and the green channel LEDs respond to input changes, the module is functionally healthy.
• PROFINET diagnostics: In the CPU's online view, the IM 155-6 PN ST should show OK for the head module. Sub-module status words should report channel quality = Good (0x80) instead of Bad (0x00).
• Process image: Force a known input (e.g., short the channel 0 RTD terminals with a precision 100 Ω resistor) and read the IW value. The value should track the expected resistance within the module's specified accuracy class (typical ±0.1% of the full-scale span for the HF variant at 25 °C ambient).
• Watch table: Insert a watch table with the AI module's input words (e.g., IW 0 .. IW 7 for the 4-channel HF module, with quality + value as defined by the channel configuration). The quality byte should be 0x80 (Good) and the value should update with the input.

If any of these checks fail, the configuration tolerance is not yet enabled. Re-verify Method 1's startup parameters and recompile the hardware configuration.

Related Module Families

The same compatibility pattern appears in other ET 200SP and ET 200AL analog modules. The most frequent field reports are:

• AI 8xI 2-/4-Wire Basic (6ES7134-6GF00-0AA1, -0AB1): ships with FS23, factory FW V2.0.0. Per ID 109791853, V2.0.0 is not available for download and a downgrade to V1.x is impossible. Stations upgrading to a newer TIA Portal must accept this as the lowest baseline.
• AI 4xRTD/TC, 4xM12 (ET 200AL, 6ES7144-6KD00-0AB1): per ID 110001521, modules with factory FW V2.0.x cannot be downgraded to versions below V2.0.0. The engineering tooling must support V2.0.0 or higher.
• AI 8xU/RTD/TC/TF HF (6ES7134-6PA00-0BD1 and similar generation): same anti-rollback policy applies starting at FS04.
• S7-1500 / ET 200SP CPUs: firmware images aggregate in ID 109478459. The most recent V4.1.4 package is the reference image for the S7-1500 / ET 200SP CPU family.

If the station uses mixed modules, perform the same "Permit operation with configured/actual mismatch" check in the S7-1200 (or S7-1500) startup parameters; otherwise one mismatched module can block the entire station.

Best Practices and Field Notes

• Always inventory the FW version printed on the module label before commissioning. The label is the authoritative factory firmware, not the catalog drop-down in TIA.
• Keep the TIA Portal installation and the ET 200SP HSP current. Siemens publishes new HSPs several times per year; an updated HSP is the cleanest way to add newer module descriptions.
• For brownfield installations that cannot move off TIA V16, set the offline firmware to the closest available older version and rely on the CPU's startup tolerance. Do not attempt to force a downgrade to V1.x – the module's bootloader will refuse the operation.
• Document the firmware tolerance in the project Functional Specification. The "Startup CPU even if mismatch" flag is a powerful override; it should be enabled only after a risk assessment that confirms the module's functional capability is acceptable.
• When the engineering organization upgrades to TIA V17 or V18, re-validate every module's configured FW in the project tree and reconcile against the field inventory. Pay particular attention to spare-part modules with newer factory firmware.
• Use ET 200SP Firmware Collection (ID 109804718) as the single source of truth for the latest FW images and release notes.

FAQ