Abstract: A network bridge between a DEC Ethernet network using LAT protocol and an Allen-Bradley Data Highway/Data Highway Plus (DH/DH+) network eliminates the need to use a DEC terminal server and Allen-Bradley KE/KF2 interface with their low data rates. A terminal server emulator is electrically connected to the DEC Ethernet network for stripping the LAT protocol from the DEC Ethernet network and provide DF1 formatted data. A converter module is electrically connected between the terminal server emulator and the DH/DH+ network for converting the DF1 data into DH/DH+ protocol data and for transmitting this data to the DH/DH+ network. The converter also converts data using DH/DH+ protocol which is received from the DH/DH+ network into DF1 data and transmits this data to the terminal server emulating means. The terminal server emulating means then places the DF1 formatted data into LAT packets and transmits the LAT packets to the Ethernet network.

Abstract: The system includes a first computer for communicating with automatic guided vehicles on a guided vehicle loop and storing information related to vehicle position. A second computer determines vehicle destinations. The first computer and the second computer maintain separate databases. Information in the data of the first computer relating to vehicle position is copied into the database of the second computer to assist in making vehicle destination determinations and the vehicle destination information stored in the database of the second computer is copied into the first computer. The invention also includes a unique fast and slow polling routine to insure that data transfer to the vehicles requiring it most is achieved in any polling cycle.