HMI Functionality
When using the Visual Studio application going with the toolbox, the following functions are available:
- The application is making connection to the board by the com port given as parameter when the application is started or the IP address (when connected to the internet via IP). When connection to the board fails, the application stops with an error message (for the parameters see the next article).
- When successfully started, the VBA application sends the @GMI message to the board. The board will than reply with all meta data in messages as described in the HMI article. Remark: When the board is started while the VBA application is already running, the board will send all meta data answering messages to the VBA application.
- When there is a match between tagname and control on the form, the VBA application is painting the background of the control light gray and will send –depending on the I/O type- a poll message or a request for data change message to the board. For matching digital I/O the @RDC message is send and for analogue I/O a @PAI message is send to the board.
- When I/O is changed on the board, the board will send the updates to the VBA program by @RDC and @PAI messages. The VBA application will update the appropriate control on the screen automatically. No additional programming necessary.
- With the VBA control “change” event, it is possible to create additional actions when a control is updated.This is up to the programmer.
The described functionality is a typical method of dynamic updating of data on a form. To perform dynamical updates, the “VBA backgroundworker” is developed to perform these functions. The background worker is receiving the messages coming from the board and then the received data is transported to the foreground of the VBA application.