TKS: Unable to load driver DLL: C:\******\drivers\siemens_s7_plus_ethernet.dll

[herve_husson]

1. Scenario: Upgrade from KepServerEX V6.11 to Thinkgworx Kepware Server V 6.16.217
2. Issue: After migration, Siemens S7 Plus Ethernet driver does not load. Error message in Event Log: Unable to load driver DLL: C:\Program Files (x86)\Kepware\KEPServerEX6\drivers\siemens_s7_plus_ethernet.dll.After checking the digital signature of the dll, the certificate in the signature cannot be verified.
3. Solution: There are 2 "dll" associated with the Siemens S7 Plus Ethernet Plus drivers:

• AGLink40.DLL
• siemens_s7_plus_ethernet.dll

Try to find on another PC/Server the certificate from the dll "AGLink40.DLL" with a "digital signature OK", then export this certificate and import it onto your server.

Reinitialize TKS, that's it that's all.

But Best Practice, when migrating from KepServerEX to Thingworx Kepware Server:

• Backup your configuration
• uninstall KepServerEX
• Install Thingworx Kepware Server

[pshashipreetham]

Hi @herve_husson , 

I assume the root cause would be:
The DLL file siemens_s7_plus_ethernet.dll requires a verified digital signature for proper loading. It depends on another DLL (AGLink40.DLL) which must also have a valid, verifiable digital signature. On some systems, the certificate for AGLink40.DLL may not be trusted or may be missing.

May be you can resolve by

• Identify Valid Certificate Source:

  • Locate another PC/server where AGLink40.DLL shows “Digital Signature is OK” (see second screenshot).

  • This indicates the certificate is fully validated on that machine.

• Export Valid Certificate:

  • On the working machine:

    • Right-click AGLink40.DLL → Properties → Digital Signatures → Select signer → View Certificate → Details → Copy to File.

    • Export the certificate (preferably as .CER file).

• Import Certificate on Problem Server:

  • Double-click the exported .CER file.

  • Click Install Certificate.

  • Select Local Machine store.

  • Choose Place all certificates in the following store → Trusted Root Certification Authorities.

  • Complete the import.

• Reinitialize Kepware Server:

  • Stop and restart ThingWorx Kepware Server services (or reboot if necessary).

Best Practice for Kepware Upgrades:

• Always backup your configuration (.opf and .ptcfg files).

• Uninstall old KepServerEX version completely.

• Install ThingWorx Kepware Server as a fresh install (not on top).

• Reimport configuration post-install.

• Validate all third-party or dependent DLLs for digital signatures post-upgrade.

Thanks,