Resolving System Expansion Card Missing Error When Downloading to SIMIT Virtual Controller

When downloading CFC charts from older SIMATIC PCS 7 versions (such as PCS 7 V8.1 SP1) into SIMIT V10 Virtual Controller, the error 'System expansion card not inserted or faulty' occurs because the SIMIT S7-410 virtual CPU model does not satisfy the hardware SEC query enforced by older CFC compilers. Resolving this issue requires swapping the S7-410 definition files in the SIMIT Virtual Controller CPU directory with the provided legacy S7-417 files, allowing the virtual controller to emulate a standard S7-417 CPU that accepts CFC downloads without SEC verification.

Root Cause of the Virtual Controller SEC Verification Failure

The SIMATIC S7-410-5H Process Automation controller relies on a hardware System Expansion Card (SEC) to authorize process object capacity. In physical hardware, the CPU firmware queries the SEC during startup and whenever the engineering system initiates a program download.

When compiling and downloading Continuous Function Charts (CFC) from PCS 7:
* CFC Versions Prior to V8.2 Update 3: In PCS 7 V8.1 SP1 (and early V8.2 releases), the CFC download driver executes an explicit hardware SEC interrogation before transferring user program blocks.
* SIMIT Virtual Controller Emulation: SIMIT Virtual Controller (VC) V10.0 provides virtualized S7-410 CPU engines. However, older CFC drivers fail to interpret the simulated SEC response returned by the virtual controller, flagging the virtual CPU as having a missing or defective expansion card.
* Compatibility Solution: Starting with CFC V8.2 Upd 3 and PCS 7 V9.0, Siemens updated the CFC download engine to natively recognize SIMIT Virtual Controllers. For earlier PCS 7 engineering stations, Siemens bundles legacy CPU definitions (_LEGACY files) inside the SIMIT installation to report the virtual controller as an S7-417 CPU, which does not require an SEC.

Step-by-Step Configuration to Enable Legacy CPU Emulation in SIMIT

Follow this procedure on every computer hosting a SIMIT Virtual Controller instance.

Prerequisites

SIMIT Virtual Controller simulation halted and the SIMIT software completely closed.
Windows administrative privileges to rename files within the Program Files directory.
PCS 7 Engineering Station network connection established to the SIMIT simulation PC.

Step 1: Navigate to the SIMIT CPU Data Directory

Open Windows File Explorer on the PC running SIMIT.
Navigate to the following installation directory:
C:\Program Files (x86)\Siemens\Automation\SIMIT\SIMIT VC\data\CPU

Step 2: Backup and Rename the Default S7-410 Definition Files

Locate the active S7-410 definition files:
* 6ES7 410 5HN08-0AB0
* 6ES7 410 5HX08-0AB0
Rename these files by appending the _CPU410 suffix:
* 6ES7 410 5HN08-0AB0 → 6ES7 410 5HN08-0AB0_CPU410
* 6ES7 410 5HX08-0AB0 → 6ES7 410 5HX08-0AB0_CPU410

Step 3: Activate the Legacy Definition Files

In the same directory, locate the legacy definitions:
* 6ES7 410 5HN08-0AB0_LEGACY
* 6ES7 410 5HX08-0AB0_LEGACY
Rename these files to remove the _LEGACY suffix:
* 6ES7 410 5HN08-0AB0_LEGACY → 6ES7 410 5HN08-0AB0
* 6ES7 410 5HX08-0AB0_LEGACY → 6ES7 410 5HX08-0AB0

Step 4: Restart SIMIT and Redownload the Program

Launch SIMIT and open the simulation project.
Start the Virtual Controller. The virtual CPU now responds to STEP 7 / CFC inquiries using S7-417 protocol framing without requiring SEC authorization.
In SIMATIC Manager, initiate the download:
* Select the S7 Program or CFC chart folder.
* Click PLC -> Download (or compile and download from CFC).
* Confirm that the transfer completes with zero SEC errors.

Verification

In SIMATIC Manager, open the module information dialog (Ctrl+D) for the simulated CPU. Verify that the operating state transitions cleanly from STOP to RUN.
Open a CFC chart and activate dynamic test mode (Debug -> Test Mode). Verify that live values cycle dynamically from the SIMIT simulation model.
Verify that NetPro and HW Config downloads complete without reporting hardware configuration mismatches.

Limitations and Operational Precautions

This file renaming workaround is specifically required for PCS 7 versions prior to CFC V8.2 Update 3. If the engineering station is updated to PCS 7 V9.0 or later, restore the original _CPU410 file names to leverage full S7-410 virtualized capabilities.
Emulating an S7-417 does not restrict program logic or memory limits within SIMIT, but hardware-specific S7-410 system function calls (such as online PO expansion test functions) will not be available.
Ensure SIMIT simulation runtime is completely terminated before modifying files in the SIMIT VC\data\CPU directory; locked files will result in access denied errors.

Engineer FAQ

Does this issue affect S7-PLCSIM?
No. Standard S7-PLCSIM does not emulate the physical S7-410 SEC interface and bypasses SEC hardware validation during program downloads.
Will downloading to a legacy-configured virtual controller alter my PCS 7 project?
No. The change exists entirely within the SIMIT virtual controller software layer. Your PCS 7 HW Config, NetPro, and CFC charts remain configured as an S7-410-5H.
Why did NetPro and HW Config download succeed while CFC failed?
STEP 7 hardware configuration tools transfer low-level station parameters without interrogating Process Object licensing; the SEC check is enforced specifically by the CFC compiler and download engine.
Can I apply this fix in a multi-node simulation with multiple Virtual Controllers?
Yes. The file modification applies globally to all S7-410 Virtual Controller instances executed on that PC.
What is the permanent solution without renaming files?
Updating the PCS 7 Engineering Station to CFC V8.2 Update 3 (or higher) permanently eliminates the SEC check against SIMIT Virtual Controllers.

Technical References

Siemens Industry Online Support Entry ID 109746485: SIMIT Virtual Controller User Guide.
Siemens SIMATIC PCS 7 System Documentation: SIMATIC S7-410 Process Automation Controller Manual.
Siemens Product Notice: SIMIT Compatibility and Operation with PCS 7 Engineering Stations.