Hi, I can write a program on the PDA device using Basic4ppc on the device and the serial port communications will work just fine. I then move the program over to the desktop and compile the program for the device. I then take the compiled (.exe) file and run it through the SetupBuilder program to generate a (.CAB) file. I list the SerialDevice.dll as one of the files to be included in the (.CAB) file. I then take the (.CAB) file and install the program on the PDA device. When I run the program the serial port communications no longer work. Does the SerialDevice.dll need to be referenced in some way? Its like the program can not find the SerialDevice.dll. Do you have any ideas on how to get the Serial Port communications working again? When compiling using the Desktop IDE for the Device, does the SerialDevice.dll file get embedded in the compiled (.exe) file? Does the SerialDevice.dll file need to be included as one of the files inside the (.CAB) file when using the SetupBuilder program?