An extender system for MIL-STD-1553 buses transparently couples bus components at multiple developer sites. The bus network extender is a relatively inexpensive system that minimizes the time and cost of integration of avionic systems by providing a convenient mechanism for early testing without the need to transport the usual test equipment and personnel to an integration facility. This bus network extender can thus alleviate overloading of the test facility while enabling the detection of interface problems that can occur during the integration of avionic systems. With this bus extender in place, developers can correct and adjust their own hardware and software before products leave a development site. Currently resident at Johnson Space Center, the bus network extender is used to test the functionality of equipment that, although remotely located, is connected through a MIL-STD-1553 bus. Inasmuch as the standard bus protocol for avionic equipment is that of MIL-STD-1553, companies that supply MIL-STD-1553-compliant equipment to government or industry and that need long-distance communication support might benefit from this network bus extender.
The state of the art does not provide a multicoupler source for this purpose. Instead, the standard used by the military serves merely as an interface between a main computer in some device or aircraft and the subsystems of that device or aircraft — for example, a subsystem that controls wing flaps or ailerons. Unfortunately, the transmission distance of a state-of-the-art MIL-STD-1553 system is limited to 400 ft (122 m). The bus network extender eliminates this distance restriction by enabling the integrated testing of subsystems that are located remotely from each other, without having to physically unite those subsystems. Interlinking by use of the bus network extender is applicable to 90 percent of all required testing for the military; hence, it offers the potential for savings in cost and time. There is also potential for commercial applications in simulation and training and in the development of real-time systems.
The bus network extender enables long-distance communications by use of specified media and compliant equipment, while conforming to all relevant MIL-STD-1553 specifications, including those that pertain to response times and data formats. The bus network extender can also insert simulated or table-driven data addressed to any bus controller (BC) or remote-terminal (RT)/support-area (SA) network combination.
In a system under test, subsystems connected at a local site are connected to the bus network extender. After the connection is made, the output of a remote bus controller mimics the activity of the bus controller at the local site and can be configured to operate with multiple remote sites. The entire bus network is then controlled by a workstation coupled at the local site. The configuration of the bus network extender is controlled by a single text file that is created by the user and that can be modified at the local site.