Applies To:
  • CitectSCADA 1.00 1.01 1.10 1.11 1.20 2.00 2.01 2.1
  • Paradox versions 3.0 4.0 

I have tried everything in the way of SQL connection strings and still can't connect to a Paradox database. 


How to access the Paradox Tables:

The Q+E database libraries that Citect (up to ver2.1) uses will access Paradox database files through Borland's Paradox Engine version 3.0. More specifically, Citect requires that you have the Windows version of the Paradox Engine's dynamic linked library (PXENGWIN.DLL) installed and in the DOS Path.

Refer to the Borland Paradox Engine User's Guide for more information on installing and configuring this product.

What version are your Paradox Tables?

In the [PARADOX] section of the QEX.INI file you should specify either Version=3 or Version=4 as appropriate for the version of Paradox that you use. For example, if you are using Paradox version 3.5 then you should specify Version=3. If absent then Citect assumes version 4. The QEX.INI file should reside in your windows directory - it may or may not already exist.

Are Multiple users trying to access the Paradox tables?

Multi-user queries can be made to Paradox tables that reside in a shared directory on a network. The Paradox tables need to be configured to allow multiple user to access / share them. This is carried out via the Paradox Engine Configuration Utility (PXENGCFG.EXE). Refer to the Borland Paradox Engine User's Guide for information on how to specify the file sharing characteristics of your Paradox Tables.

Whenever a Paradox file, that is already in use by another user, is opened, then the consistency of the data will become an issue if both users are updating the file. For this reason, before a record is modified or deleted, Citect will attempt to place a lock upon it (the record). If the record exists then the operation proceeds accordingly. If the record is already locked by another user, or it doesn't exist (for example, another user has already deleted it), then an error will be reported. The error message can be retrieved through the cicode function SQLErrMsg().

For a Citect user and a Paradox user to simultaneously access the same table, the Paradox user must have selected "Co-Edit" mode for the table.