FAQ - Frequently asked questions and their answers

?Which performance can be achieved by the TwinCAT Database Server?

! That's much too sweeping a statement. The performance depends on the used hardware, the used write mode e.g., ring buffer mode and the count of the variable which must be logged. Another aspect is the used database type.

?Supports the TwinCAT Database Server Stored Procedures?
! Yes, the TwinCAT Database Server support Stored Procedures with the help of the PLC function blocks FB_DBStoredProcedures and FB_DBStoredProceduresRecordReturn. These function blocks are not supporte by every database type.

?Which data types are supported by the TwinCAT Database Server?
! This Link shows all supported databases of the TwinCAT Database Server.

?Is it possible to log more than one variable of a symbol group in one data record?
! Symbol groups will be created at the TwinCAT Database Server Configuration Editor. The declared symbols can only be logged separately into the database. To log several variable into one data record, use the function block FB_DBRecordInsert_Ex out of the PLC.

?How do I write or read single variable out of an existing database structure?
! With the help of the PLC function block FB_DBRecordInsert_Ex it is possible to write single variable into an existing database structure. Reading of single variable can be done by the function block FB_DBRecordSelect_Ex.

?Is it possible to log several data records at the same time into a database?
! This depends on the used database. The database type "Microsoft SQL Database" supports this in conjunction with the function block FB_DBRecordInsert_Ex. You only must seperate the different SQL INSERT commands with ";".

?Which network topologies are supported by the TwinCAT Database Server?
! It exists several possibilities to use the TwinCAT3 Database Server in a network. This Link shows the different supported network topologies und further information about this topic.

?Which functionalities of the TwinCAT Database Server can be used for the database type "XML"?
! The database type "XML" supports the full functionality of the TwinCAT Database Server. Only Stored Procedures and Delete SQL commands are not supported. You can work with the XML file like every other database with SQL commands, or with the cyclic write mode of the PLC values. An additional functionality is the possibility to use XPath commands and read XML-Tags. For further information look here.

?Why are some Function Blocks in an "Obsolete" folder?
! During the product development it gives new PLC function blocks which include the functionallity of older function blocks. Specially in new projects it makes no sense to use the obsolete FB's. Of course, the old function blocks are still part of the product. Here are the details:

• FB_DBAuthentificationAdd could be replaced by FB_DBConnectionAdd
• FB_DBRecordInsert could be replaced by FB_DBRecordInsert_Ex
• FB_DBRecordSelect und FB_DBRecordSelect_Ex could be replaced by FB_DBRecordArraySelect
• FB_DBStoredProcedureRecordReturn could be replaced by FB_DBStoredProcedureRecordReturn

?Which databases, supported by the TwinCAT Database Server, could be connected over network?
! It is not possible to reach all databases, which are supported by the TwinCAT Database Server, over network. Here a list of all databases which must be used locally on device:

• Microsoft Access Database
• Microsoft SQL Compact Database
• XML Database
• ASCII File

All other supported databases can be connected over network!