Abstract: An electronic data processing system comprises a first application program that is capable of operating in a first mode and a second mode. The first mode comprises software emulation of a vehicle data bus and one or more network elements. The second mode comprises communications access to the vehicle bus and the one or more network elements. The electronic data processing system is capable of executing an operating system. A virtual bus server application comprises a shared memory and a message router. The operating system facilitates communication between at least two dynamic link libraries in shared memory. The message router is capable of routing data messages between the first application and a first hardware module as a network element in the second mode. A first dynamic link library interface provides an interface between the first application program and the virtual bus server application.

Abstract: A system for determining the relative position of first and second farm vehicles, each equipped with a satellite-supported position sensing device. A data transmission link transmits position data between the vehicles, and a computer on one of the vehicles determines data with respect to the relative position of the vehicles. A control device responsive to satellite signal quality assures that the two position sensing devices operate in the same reception modes for improved accuracy.