Comments by contributor Julian Stone:

The following attached project uses a class called rs232 which is freely available on the net. I have corrected what I think was a slight error in your sendCommand function. I have also added a function and a sub which read and write to the EEPROM area, and two buttons to test these. Apart from that it should function in the same way as your VB6 version.

Click here to download project files:  TrilogiDotNetComms.zip