Abstract: The present invention provides a method and apparatus for facilitating communication with non-fault tolerant network nodes in a fault-tolerant network environment. In various embodiments, a network address or network location of any network nodes present on a network that are not fault-tolerant is determined and stored, and data intended for the detected non-fault-tolerant network nodes is routed only over that network to which the non-fault-tolerant network node is connected. In further embodiments, the fault-tolerant network comprises a primary and redundant network with fault tolerant network nodes that are attached to each network; a non-fault-tolerant network node that is attached to either the primary or redundant network is then operable to communicate with any fault-tolerant network node via data sent over only the network to which the non-fault-tolerant network node is connected.

Abstract: A distributed control system architecture (HSE) provides an open, interoperable solution optimized for integration of distributed control systems and other control devices in a high performance backbone, provides an open, interoperable solution that provides system time synchronization suitable for distributed control applications operable over a high performance backbone, and provides an open, interoperable solution that provides a fault tolerant high performance backbone as well as fault tolerant devices that are connected to the backbone. The distributed control system architecture comprises a High speed Ethernet Field Device Access (HSE FDA) Agent, which maps services of a distributed control system, e.g., a fieldbus System, to and from a standard, commercial off-the-shelf (COTS) Ethernet/Internet component.

Abstract: An apparatus controls the movement of a data block between a peripheral and a data processing system, which comprises a bus which includes an address bus, a first data bus, and a second data bus, the peripheral being connected to the second data bus. A first memory, connected to the second data bus, stores data, and a second memory, connected to the first data bus, stores a plurality of dummy routines in predetermined areas, the predetermined areas of the second memory having corresponding buffer areas in the first memory. The first memory and the second memory correspond to a first memory area and a second memory area within a total predefined memory space, each memory location within the total memory space being defined by a unique memory space address. A processor connected to the first data bus, fetches an instruction, in response to a control signal from the peripheral, from a preselected one of the dummy routines.

Abstract: A bidirectional repeater for Manchester encoded data (MED) signals present on a coaxial cable and fiber optic cable forming the transmission media of a local area network. The repeater receives and then reconstitutes the MED signals present on the coaxial cable and transmits the reconstituted MED signals onto the fiber optic cable. MED data present on the fiber optic cable is received, reconstituted, and transmitted onto the coaxial cable. Signals can be received from only one cable at any one time. Transmission of reconstituted MED signals is terminated when a special set of MED signals identifying the end of a transmission by a module of the network is received.

Abstract: In a local area network having a plurality of nodes, wherein the local area network utilizes a token passing scheme for communicating between nodes, each node has an interface apparatus which operates independently of a processor associated with the node. The node can be in an on-line mode or an off-line mode, wherein the node does not participate in token passing or receive information when in the off-line mode. A method of the present invention provides for diagnosing and/or recovering a second node from a first node, the method implemented by the second node includes the steps of waiting to receive a message frame addressed to the second node. If the message frame addressed to the second node is a special function frame, and if the second node is in the off-line mode, the type of special function frame is determined to perform the command specified by the type of special function frame. The operation of the second node then returns to the step of waiting to receive a message frame addressed to it.

Abstract: A detector of predetermined patterns of Manchester encoded data signals in which the voltage levels of the half-bit cells of "n" sequential Manchester bit cells, where "n" is an integer greater than zero, are clocked into a shift register, the pattern of 2 "n" voltage levels of 2 "n" half-bit cells of the "n" sequential Manchester bit cells stored in the register at any given time are examined by a programmable logic array which produces an output signal when the pattern of outputs of the shift register corresponds to the predetermined patterns.

Abstract: The method by which the right of access to the common communication medium of an initialized local-area network is transferred between modules having access to the medium by the module having such access transmitting a token to a designated existing and properly functioning module. Each such module is assigned a unique address, its MY ADDRESS, and has the data-processing capabilities to determine and store the address of the module to which it last successfully transferred a token, its LAST SUCCESS ADDRESS. Each module also determines the address of a module, if any, between its LAST SUCCESS ADDRESS and its MY ADDRESS, its TRY ADDRESS. The module which has accepted a token will try to pass a token to the module whose address is that of its TRY ADDRESS if its TRY ADDRESS differs from its LAST SUCCESS ADDRESS before attempting to pass a token to the module whose address is that of its LAST SUCCESS ADDRESS.

Abstract: The method by which a token-passing local-area network having from two to 2.sup.n modules is initialized, where n is an integer greater than zero. When connected into the network and energized, each module determines if the network is initialized and, if not, which module is to do so. Each module has a unique n bit network address. The module with the smallest network address energized before the network is initialized is identified and begins the process of initialization by transmitting tokens addressed sequentially to network addresses beginning with the next higher address than its own until a token so transmitted is accepted by an addressed module or until a token has been addressed to all network addresses other than that of the initiating module. If after tokens are transmitted to all possible network addresses other than that of the initiating module, the initiating module generates a fault signal to indicate its status.

Abstract: A decoder for Manchester encoded data signals in which the encoded data signals are applied to a first circuit which produces a primary pulse at each voltage transition of the applied signals. The primary pulse enables a delay line oscillator which after a predetermined period of delay produces a decode clock signal of a given frequency. The inverted primary pulse, the decode clock signal, and a constant voltage data input signal are applied to a decoder shift register. The primary pulse and selected outputs of the decoder shift register are applied to a logic circuit which produces a receive clock signal having desired low-to-high voltage transitions occurring substantially in the center of each half-bit cell of a Manchester bit cell. The receive clock signal can be applied to a receive data shift register to which the encoded data signals are also applied so that the binary value of each half-bit cell of a Manchester bit cell can be stored in the data shift register.