Abstract: A local area network having fault detection and recovery and a method for detecting and recovering from faults in a local area network are disclosed. The network has modules interconnected by a token bus implemented by a pair of redundant cable systems. All of the modules are agent modules and one of the modules also serves as a master module. Each agent module periodically transmits an agent heartbeat signal on each of its cables. Each module monitors all of the agent heartbeat signals from all of the other modules. When a fault is detected by a module, such as missed agent heartbeat signals from another module, the module applies agent rules to determine if and how the fault should be reported. The agent module reports the fault to the master module. The master module collects fault reports from the agent modules, applies a set of master rules to the agent fault reports, and generates a master failure report.

Abstract: Application interface software provides communication between a network of computer nodes and user applications of a host processor. Interpreters or gateways are used between the host processor and the network of computer nodes. The application interface software employs a redundancy routine to ensure host access of computer node data through the gateways. The redundancy routine changes access of computer node data from one gateway to a second gateway during times of dysfunctioning of the one gateway. The redundancy routine changes access in a manner which is transparent to the host processor. A database is employed to hold computer node data for direct access by the host processor. The redundancy routine ensures the latest computer node data values to be reflected in the database.