In your situation better is to split two parts (communication and user interface) in separate applications. In other case communication through MSComm control will be very strong dependent of user interface and often will cause time-out errors. In example, our POS system, that communicates through MSComm with many ECRs (polling them), is splitted into two parts: ECRServer (written in VB), which communicates with ECRs, and CashReg (written in VFP), that stores data about sells. Two parts communicate each other using our FoxSock control, which is usable in VFP wrapper around WinSock control.