Project planning support

A selection of the process variables used must already be made in the visualisation during the creation of a PLC program.

Information about the data type, access and address of each process variable must be entered in the visualisation project file. Many PLC programming environments generate a list of process variables, the transfer of which via a selection dialogue facilitates the work of the visualisation developer. There are also differences here for the possible communication components:

• VisiWin drivers do not include a transfer interface. The information for each process variable must be entered manually in the project file.
• The OPC specification includes the browser interface. Here, the variable definitions can be transferred to the visualisation project via a selection dialogue. However, it should be noted that browsing is sometimes linked to boundary conditions. For example, some OPC servers expect a connected PLC when browsing. When transferring data via a network, difficulties may arise with the correct DCOM configuration and, finally, it is up to each manufacturer of an OPC server to decide whether it supports browsing at all.
• VisiWinNET drivers also contain an (optional) interface for simple variable transfer. In addition, the manual creation of variables in the project file is simplified by a dialogue that contains a mask for the supported addresses and data types of the PLC.