C135 PCS 7 (PCS7)
6C
6 Cielo Ciencia y Tecnología
·Publicada en C135 PCS 7 (PCS7)

Resolving Method Open Missing Errors When Referencing SIMIT API Coupling v10.3 in SIMIT v10.2

Resolving Method Open Missing Errors When Referencing SIMIT API Coupling v10.3 in SIMIT v10.2

Referencing the Siemens.Simit.Api.Coupling assembly from SIMIT v10.3 within a SIMIT v10.2 runtime environment causes a runtime MissingMethodException ('Method Open is missing') due to binary assembly incompatibility and structural signature changes introduced in the v10.3 API. Custom external couplings compiled against SIMIT API v10.3 cannot execute against the v10.2 runtime core. To resolve this issue, you must compile your external coupling against the exact assembly version matching the target runtime installation (Siemens.Simit.Api.Coupling v10.2 for SIMIT v10.2 targets), or configure multi-targeting in your .NET project to output separate build artifacts for each SIMIT release version.

Table of Contents

Executive Summary

Custom external couplings in SIMIT leverage the .NET-based Siemens.Simit.Api.Coupling.dll assembly to establish high-speed inter-process communication, shared memory access, and cyclical signal exchange between custom simulation engines and the SIMIT runtime kernel. When upgrading development environments or attempting to share custom coupling binaries across mixed SIMIT installations, developers frequently encounter binary runtime incompatibilities. Specifically, deploying a coupling assembly built against SIMIT v10.3 onto a host running SIMIT v10.2 causes the application to crash upon startup with a missing method exception targeting Open or IPC initialization routines.

Because the SIMIT API relies on strong-named assemblies and version-specific C++/.NET interop boundaries, backward compatibility across major and minor releases is not guaranteed. New overloads and interface refactorings introduced in v10.3 are entirely absent from the v10.2 global assembly cache and local binary directories. This guide provides the architectural rationale behind this limitation, detailed multi-target build procedures in Microsoft Visual Studio, assembly binding redirection guidelines, and verification tests to ensure seamless external coupling deployment across varied engineering workstations.

Architecture and Fundamental Mechanics

The SIMIT external coupling architecture operates as an out-of-process or in-process managed bridge connecting external simulation tools (such as MATLAB/Simulink, Python wrappers, or custom C# modeling engines) to the SIMIT runtime engine (SimitRuntime.exe). The core API contract is defined within Siemens.Simit.Api.Coupling.dll, which implements interface contracts such as ICoupling, ISimulationControl, and signal collection accessors.

Between SIMIT v10.2 and v10.3, Siemens restructured the IPC initialization pipeline to support enhanced asynchronous memory mapping, multi-threaded signal dispatching, and extended data types. As part of this refactoring, the signature of the Open() method on the primary coupling manager was modified—either through the introduction of additional mandatory initialization parameters, cancellation tokens, or by migrating from a synchronous return structure to an asynchronous task pattern.

When a managed .NET application attempts to execute a method at runtime, the common language runtime (CLR) JIT compiler attempts to resolve the exact method metadata token matching the compiled assembly reference. When an external coupling compiled against Siemens.Simit.Api.Coupling v10.3 is executed inside a SIMIT v10.2 host:
1. The CLR locates the v10.2 assembly installed in the SIMIT program directory (C:\Program Files (x86)\Siemens\Automation\SIMIT\SIMIT SF\bin or GAC).
2. The runtime compares the assembly metadata token requested by the caller against the metadata table of the loaded v10.2 DLL.
3. Because the v10.3 signature of Open(...) does not exist in v10.2, the JIT compiler throws System.MissingMethodException: Method 'Open' in type 'Siemens.Simit.Api.Coupling.Coupling' not found.

Assembly binding redirection via app.config cannot resolve this error because the physical code implementation and parameter list required by the v10.3 assembly do not physically exist inside the v10.2 binary.

Step-by-Step Implementation Procedure

Step 1: Segregate SIMIT API Reference Assemblies

  1. On your software development workstation, extract and store version-specific copies of the SIMIT API libraries into dedicated project repository directories:
    * lib/Simit_v10.2/Siemens.Simit.Api.Coupling.dll
    * lib/Simit_v10.3/Siemens.Simit.Api.Coupling.dll
  2. Never rely on hardcoded paths pointing directly to C:\Program Files (x86)\Siemens\Automation\SIMIT\... on your build machine, as this ties the compiled output strictly to the locally installed SIMIT version.

Step 2: Configure Multi-Targeting or Conditional Compilation in Visual Studio

  1. Open your external coupling project file (.csproj) in Visual Studio or an XML editor.
  2. Configure conditional compilation configurations or build configurations for both SIMIT versions:
    xml <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release_v10.2|AnyCPU'"> <DefineConstants>TRACE;SIMIT_10_2</DefineConstants> <OutputPath>bin\Release_v10.2\</OutputPath> </PropertyGroup> <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release_v10.3|AnyCPU'"> <DefineConstants>TRACE;SIMIT_10_3</DefineConstants> <OutputPath>bin\Release_v10.3\</OutputPath> </PropertyGroup>
  3. Define conditional assembly references based on the selected build target:
    xml <ItemGroup Condition="'$(Configuration)' == 'Release_v10.2' Or '$(Configuration)' == 'Debug_v10.2'"> <Reference Include="Siemens.Simit.Api.Coupling"> <HintPath>..\lib\Simit_v10.2\Siemens.Simit.Api.Coupling.dll</HintPath> <Private>False</Private> </Reference> </ItemGroup> <ItemGroup Condition="'$(Configuration)' == 'Release_v10.3' Or '$(Configuration)' == 'Debug_v10.3'"> <Reference Include="Siemens.Simit.Api.Coupling"> <HintPath>..\lib\Simit_v10.3\Siemens.Simit.Api.Coupling.dll</HintPath> <Private>False</Private> </Reference> </ItemGroup>

Step 3: Implement Conditional Initialization Logic in C# Source Code

  1. In your coupling lifecycle management class, wrap the connection initialization method using preprocessor directives:
    csharp public void InitializeCoupling(string projectName) { #if SIMIT_10_2 // SIMIT v10.2 signature _coupling = new Siemens.Simit.Api.Coupling.Coupling(); _coupling.Open(projectName); #elif SIMIT_10_3 // SIMIT v10.3 signature with updated parameters/flags _coupling = new Siemens.Simit.Api.Coupling.Coupling(); _coupling.Open(projectName, CouplingMode.Standard); #endif }

Step 4: Build Version-Specific Deployment Binaries

  1. In Visual Studio, select Build > Batch Build.
  2. Compile both Release_v10.2 and Release_v10.3 build targets.
  3. Verify that the output folders contain separate binaries compiled specifically against the matching reference DLL.

Step 5: Deploy the Matching Binary to the Target Host

  1. Identify the exact SIMIT version installed on the target machine by checking Help > About SIMIT in the SIMIT UI.
  2. For SIMIT v10.2 hosts, copy the binary from bin\Release_v10.2\ into the host application or coupling directory.
  3. For SIMIT v10.3 hosts, copy the binary from bin\Release_v10.3\.

Verification

  1. Launch SIMIT v10.2 on the target engineering machine and open your simulation project.
  2. Launch your custom external coupling application built with the Release_v10.2 target profile.
  3. Confirm that the application initializes without dialog prompts displaying MissingMethodException or TypeLoadException.
  4. In the SIMIT coupling overview editor, verify that the external coupling status transitions from 'Disconnected' to 'Connected'.
  5. Start the SIMIT simulation runtime and verify bidirectional signal exchange: force a boolean signal in the external application and verify that the corresponding input signal updates in the SIMIT chart within one simulation time step.

Limitations and Operational Precautions

  1. Upward and downward compatibility across minor SIMIT API versions is not guaranteed by Siemens; external couplings must always be validated against each specific SIMIT release.
  2. Assembly binding redirects in .config files cannot bridge binary incompatibilities where method signatures or types have been modified or deleted.
  3. The external coupling process must run with appropriate Windows user privileges matching the SIMIT host process to allow shared memory and named pipe communication.
  4. Avoid setting <Private>True</Private> (Copy Local) for Siemens.Simit.Api.Coupling.dll in deployment directories, as loading a local DLL that conflicts with the host SIMIT runtime directory causes assembly loading deadlocks.

Engineer FAQ

Why did SIMIT v10.3 change the method signature of Open in the Coupling API?

SIMIT v10.3 introduced internal enhancements to asynchronous simulation coupling, expanded thread safety models, and updated shared memory handshakes. These architectural improvements required modifying the underlying Open initialization signatures.

Can I use an assembly binding redirect in app.config to force SIMIT v10.2 to accept v10.3 assemblies?

No. An assembly binding redirect only redirects assembly identity (version numbers). If the target assembly does not physically contain the requested method signature, the CLR immediately throws MissingMethodException.

Can a coupling compiled against SIMIT v10.2 run on SIMIT v10.3?

In some cases, forward compatibility functions if the v10.3 runtime maintains backward-compatible legacy overloads. However, Siemens strongly recommends recompiling external couplings against the native v10.3 API to ensure stability.

Where can I find the official documentation for the SIMIT API Coupling?

The API documentation and code samples are included in the SIMIT installation directory under the Manuals folder and in the Siemens Industry Online Support portal under the SIMIT simulation manual collection.

Do I need a separate SIMIT license to develop and execute external couplings?

Executing an external coupling requires a SIMIT runtime license (such as SIMIT Standard or SIMIT Professional). The Coupling API assemblies themselves are included with the SIMIT engineering installation. Consult an authorized Siemens distributor or the Siemens Industry Mall for exact simulation licensing terms.

Technical References

Related Articles

Related Tags

  • SIMIT V10.2
  • SIMIT V10.3
  • Coupling API
  • DotNet Interop
  • Simulation
20 respuestas