Enable Automatic Updates of TLS Versions for CtAPI Applications

Plant SCADA runtime will use the most secure versions of the Transport Layer Security (TLS) protocol available based on the Windows version of the client & server computers (see Encrypted Communications for more information).

To automatically use the latest version of the TLS protocol when they are supported by Windows, a CTAPI application's executable (the .exe file) must be a managed executable that targets .NET Framework 4.7 or later.

If this is not the case (for example, your application is implemented as a .dll file that is hosted in another process which cannot be made into a managed executable), then the application will be restricted to using TLS 1.2 and 1.3. Updates to these versions will only be applied to the application if a Plant SCADA monthly update includes new versions of the TLS protocol.

For executables written in C# or Visual Basic, the executable will always be a managed executable and should target .NET Framework 4.7 or later by default if using a recent version of Microsoft Visual Studio. Check the project's property pages to confirm the version of .NET Framework being targeted.

For executables written in C++, the executable must be compiled with the /clr option to build a managed executable. In Visual Studio, use the following steps to change this option:

1. Display the Property Pages dialog for the project.

2. Ensure the Configuration and Platform selection is set to All Configurations and All Platforms if required.

3. Select the Advanced property page.

4. Under 'C++/CLI Properties', change the following options:

   • Set Common Language Runtime Support to .NET Framework Runtime Support (/clr).

   • Set .NET Target Framework Version to the required version (for example, 'v4.8').

5. Press OK or Apply to implement the changes.

If you are using a different development environment, consult the appropriate documentation for your environment.