What is a CPX port or driver?
CPX ports are virtual ports that use your existing COM ports to communicate with your Datacard printer. No additional hardware is needed. Setting up an additional port in this way tells Windows to use a software component (called a Port Monitor) for printing to your Datacard printer. 


From: http://www.datacard.com/downloads/ViewDownLoad.dyn?elementId=repositories/downloads/xml/150i_2XX_PrinterDriverInstructions_Win95-98.xml&amp;repositoryName=downloads&amp;index=0