Applies To:
  • CitectSCADA 5.21

SQLDisconnect() does not release all the resources used by SQLConnect().

The resources are mainly in the form of handles (as shown by the task manager).  After repeated calls to SQLConnect() and SQLDisconnect() the system runs out of resources and will not function properly. E.g. a call to SQLExec() will fail. 

The problem exists in a third party library used by Citect for ODBC.

The best way around this is to use less calls to SQLConnect() and SQLDisconnect(). For example call SQLConnect() on page entry and call SQLDisconnect() on page exit, instead of calling these every time a button is pressed. Otherwise simply call SQLDisconnect() on shutdown for each database connection.

CIT has confirmed this to be a problem in Citect for Windows version 5.21 We are researching this problem and will post new information here as it becomes available.