By default Smart OPC XML Server service is running under Local System account. If you change the account, you must assure the following:

The service account must have write access to the C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files folder. You can assign the service account to the IIS_IUSRS group which already has;

The service account must be able to start HttpListerner at specified url. You have to execute the following command for example (chage the url and user with the appropriate ones):

netsh http add urlacl url=https://+:9443/ user=Everyone listen=yes

The service account must have write access to the entire service installation folder (e.g. C:\Program Files\Smartsys Ltd\Smart OPC XML Server);

If you use HTTPS, you have to grant access to the private key of the server certificate to the service account using Windows HTTP Services Certificate Configuration Tool (WinHttpCertCfg.exe). You can download it from here. You have to run the following command as example:

C:\Program Files (x86)\Windows Resource Kits\Tools\WinHttpCertCfg.exe -g -c LOCAL_MACHINE\MY -s "SmartWebSite" -a "SmartWebViewOnly";

Where the SmartWebSite is the common name of the certificate and SmartWebViewOnly is the service account name for example;

Open the Web.config file in the root service installation folder (e.g. C:\Program Files\Smartsys Ltd\Smart OPC XML Server\Web.config), locate the following:

<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
   <probing privatePath="Lib" />
</assemblyBinding>

and change the privatePath="Lib" to privatePath="Lib;Bin"

<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
   <probing privatePath="Lib;Bin" />
</assemblyBinding>

Thus required libraries will be found when starting up.

Remark: This is needed if ASP .NET libraries are not installed.