In the third tutorial the console interface on the PC is replaced by a GUI interface in order to demonstrate, how an interface between RTDX and a graphical user-program can be realized. In addition the application package RTDX_Service_3 is used, which realizes 4 channels between the user program on the PC and the DSP-board - one write-channel for commands and one corresponding read-channel for the direct (e.g. error) response, and in addition one write- and one read-channel for data. In this tutorial the user program sends a command via the command channel cchan to the DSP-board, receives an acknowledgment via the response channel rchan, then sends data to the client via channel ichan and receives data via channel ochan.
As GUI the multi-platform C++-program package wxWidgets is used. It can be downloaded freely from the project's home page http://www.wxwidgets.org and it is easy to integrate into 'Visual C++'. In principle also other C++-compilers can be used (see the documentation of wxWidget), but for special COM data-types and COM support-programs a 'Visual C++'-environment is needed.
The C++-package RTDX_Service_3 is listed in Appendix B.2. The basic operation is similar to RTDX_Service_2. Together with the listing a definition of the available functions is given in Appendix B.1.
To compile and run the program Tutorial_3, you should first download the complete source code: listings included in the tutorial are not complete because of size. For compiling the host part on the PC, 'VC++ 6.0' or higher and the 'wxWidgets'-package is needed. The compilation can either be done directly in Visual C++ or with the help of DialogBlocks, a wxWidgets-IDE that can be freely downloaded with limited but sufficient functionality for this tutorial from the web-page www.anthemion.co.uk/dialogblocks.