Applies To:
  • CitectSCADA 5.20, 5.21 Service Pack

When I try to connect to the Citect OPC server from a 3rd party OPC client, I get an error like: CoCreateInstance: Class not registered or... COM/OPC error 0x8007007E on CoCreateInstance() Error string: The specified module could not be found. 

Additional: Could not connect to server 'Citect.OPC'


These errors can occur if Citect 5.20 or 5.21 is installed in one directory and another copy or version is installed in a different directory. When Citect is installed, it registers COM objects that it uses with its OPC server and for Tag Import / Export / Linking.  After that, these features will no longer work for the other installations of Citect since the objects will be registered to the latest Citect installation directory only.  If the copy of Citect that you want to use OPC or Tag Import features with does not work, the easiest way to fix this is to re-install that copy of Citect.  This will re-register the objects to that Citect directory.  If you cannot do that, or that did not fix it, you can manually correct the path in the registry settings using Windows RegEdit.exe. 

Fix all of these keys that exist in your registry (some may not exist): 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{28B9E8A1-8E26-11d1-9326-00802963D3A4}\InprocServer32 (Default) = C:\CIT520\Bin\MSDAOSP.DLL 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{41972D01-8B14-11d1-931B-00802963D3A4}\InprocServer32 (Default) = C:\CIT520\Bin\ciascdrv.dll 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{44F924F1-C367-11d1-A0CB-00805F35F8B0}\InprocServer32 (Default) = C:\CIT520\Bin\cidbfdrv.dll 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{44F924F2-C367-11d1-A0CB-00805F35F8B0}\InprocServer32 (Default) = C:\CIT520\Bin\MSDAOSP.DLL 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{4EE39DA1-0CB6-11d2-8A20-00802963D3A4}\InprocServer32 (Default) = C:\CIT520\Bin\cimitsubishidrv.dll 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{4EE39DA2-0CB6-11d2-8A20-00802963D3A4}\InprocServer32 (Default) = C:\CIT520\Bin\MSDAOSP.DLL 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{BA198B61-32E3-11d1-A1B5-00805F35623C}\InprocServer32 (Default) = C:\CIT520\Bin\CtOpc32.dll 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{BA198B61-32E3-11d1-A1B5-00805F35623C}\LocalServer32 (Default) = C:\CIT520\Bin\CTOPC32.EXE 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{dfc8bdc0-e378-11d0-9b30-0080c7e9fe95}\InprocServer32 (Default) = C:\CIT520\Bin\msdaosp.dll 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{E455B364-67AE-11d1-92E9-00802963D3A4}\InprocServer32 (Default) = C:\CIT520\Bin\citrans.dll 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{FDB66A50-3E35-11d2-AEF2-00805F031A5E}\InprocServer32 (Default) = C:\CIT520\Bin\ciopcdrv.dll 

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{FDB66A51-3E35-11d2-AEF2-00805F031A5E}\InprocServer32 (Default) = C:\CIT520\Bin\MSDAOSP.DLL