Applies To:
  • CitectSCADA 5.31, 5.4x
  • CitectHMI 5.31, 5.4x

We are using the S7NT driver to communicate to a Siemens S7 PLC. Citect will crash on startup when the Trend Server is enabled. We are using Simatic Net V6.0 (07/2001 CD). 

This is a problem in the Simatic Net V6 version that you are using. You need to obtain Servicepack 4 or higher for Simatic Net V6.

The problem only occurs when Citect is using our S7 drivers with Softnet V6, and effects our COM components. It appears that the s7oxdbmx dll (from Siemens) that our S7 drivers use (indirectly through the Siemens S732.dll ) are placing a call to CoUninitialize() or OleUninitialize(). This is uninitialising the use of COM for the Citect thread and results in the release all of our COM components. The Citect Trend system is dependent on some of these COM components

(We have also seen similar problems for 3rd party ActiveX components; suddenly they did not work anymore when Simatic Net V6 was installed on that PC.)

There exists a solution and also a workaround for this problem.


Siemens has fixed this problem in Simatic Net V6 in servicepack 4 for Simatic Net V6. The CD is called "SIMATIC NET CD, PC / Windows, 07/2001 + SP4". A download from the Siemens website is currently not available. You must contact your Siemens branchoffice to obtain this CD.


For Citect V5.41 you can also use a workaround in Citect, to get around this Siemens issue.------------------------------------------------------------------

If you delete or rename the Ctversion.xml file in the Citect\BIN folder, the crash when using the Citect Trend server no longer happens on startup.

Only side effect is that on startup you will get a splash screen saying 'special build' in big red letters diagonally over the Citect splash bitmap. (this is because the .xml file has disappeared. The 'special build' splash bitmap also appears if you run Citect V5.41 on a machine with Internet Explorer 4, or any version of IE that does not support XML).

This workaround only works for V541, since in V540 there is no ctversion.xml and no ctversion.dll file in the Citect\BIN folder. So people who are now using v540 will have to go to v541 to be able to use this workaround.

(Using Softnet V5 is also a valid workaround).