"The specified key is not present in this container" error when attempting to build a Simulink model with C Caller function blocks

Hi,

I have inserted some C Caller function blocks in a model which call functions from a dll located within a C:\Program Files directory on Windows.

Simulink didn't seem to like linking to the dll in its original installation location so I copied it and the matching .lib file to the Simulink project folder.

When I try to build the model, Simulink reports "The specified key is not present in this container", but it is not clear what it refers to. I suspect it is something to do with the configuration settings which I have attached here. If I generate a new configuration file without reference to the dll and add a sine wave block plus scope (C caller blocks are commented out), it builds.

Any ideas on what is causing the issue would be much appreciated.

Answer 1

[Mark McBroom]

The configuration should only refer to the .lib file. This is the only file needed for linking. Use double quotes around the .lib path name to avoid having to copy the .lib file to the same directory as the model.

[HM]

Hi Mark,

Many thanks for your response.

I updated the configuration to only refer to the .lib file and as the C Caller blocks were placed in a library, I had to update the configuration file there.

Unfortunately, I get the same issue when I try to build the model.

Presumably the .lib file is for pulling in the static library when building custom code? I'm not intending to build custom code from the model. Its for accessing API functions to control hardware. I suspect I can use MATLAB Functions to call the dll functions calls. The C Caller blocks would be interesting though.

[Mark McBroom]

I did some more checking on this error message. The error is coming from areas of the Simulink that are not related to calling external C code. Does this error go away if you remove the C Caller blocks from your model?

[HM]

The error persists if I remove the C caller blocks.

I've tried changing the configuration settings for the model but the issue persists. I've also set the solver to a fixed-step one.

If I create a new model with just a sine wave and scope block, there is no issue with the default configuration settings.

[HM]

Update: I tried to create a new configuration from scratch in a new model.

If I tick the option to 'Simulate custom code in a separate process' in the Simulation Target pane, I then get the "The specified key is not present in this container" message.

If I untick this option but leave the option to Import Custom Code, I get the following error:

Simulink could not create a link to the shared library file 'C:\Program Files\Pico Technology\SDK\lib\ps2000.dll' inside the build directory '<project folder>\slprj\_slcc\0daaxHsGpdNw1zKl7RsFGC'. This is required by the custom code build process so that the shared library can be successfully linked by the linker.

Caused by:

Windows does not allow creating a hard link from inside the build directory to a shared library (DLL) if the DLL is located in a network folder or a different drive. Both the DLL and the build directory must be placed in the same drive, and this drive must be a local (non-network) drive. Note: original error message from Windows: Access is denied.

Is there a way to turn off the code generation capability if you just want to call the library functions?

I can call the functions to connect and disconnect using MATLAB Function blocks although I have to use coder.extrinsic for certain functions (e.g. strcat) to enable it to work.

[Mark McBroom]

Is your configuration still referencing the DLL in the Custom Code section? As I stated earlier, you should not reference DLLs in this section... only the associated .lib.

[HM]

I've double checked to ensure that the dll is not being referenced in Custom Code section:

The include directory is also set to the 'inc' folder of the SDK shown above.

I have removed any sub-folders in the slprj file and also ensured that the location of the header and dll are not on the MATLAB path - I ran the following as a check and confirmed that the dll could not be found:

which ps2000.dll

Is there anything else that I can check?

[HM]

I've run some further tests:

1. I opened MATLAB & Simulink as an Administrator - if I open just the model and library files, I am able to use the C Caller blocks. If I open the project, and attempt to run the model, that also works. I realised that the dll was present in some of the build folders but I deleted it and repeated the tests and that is fine.
2. If I start MATLAB & Simulink as normal, I can open the model and library file, and run the model. However, I get the error if I try to run the model having opened the project.

Could this be down to something in the project settings related to compiling the model/code generation? I'm not developing the model for code generation purposes.

Many thanks,