Do you have a software example for VB.NET where i can see how to access the matrix keyboard interface ?
With NetDCU, you don't need special software to get keystrokes from matrix keyboard interface. This is the same for eVC, VB.NET and C#. All what you must do, is to configure the matrix keyboard driver with the right registry settings. You find more information about this in documentation "NetDCU-Device Drivers".
Keep in mind, that matrix keyboard, digital-I/O and optional drivers like I2C/SPI can use the same PIN's. So carefull configuration is very important.