Abstract: A high reliability network provides for measurements of network delays through pairs of transmissions of local clock values used in a first message to deduce clock value offsets and in a second message to reveal network delays.

Abstract: A highly reliable industrial control system provides for the processing of redundant control signals on as little as a single serial network without overloading the network by preprocessing input signals for coincidence and sending only the coincidence signal either periodically or on a change of state. Further compression of sent data is realized by extracting a reduced subset of transmission states from the input signals and transmitting only the transmission states.

Abstract: A highly reliable industrial control system is produced such as may use a standard network for configuration by symmetrically transmitting configuration data to intercommunicating controller components. The configuration data provides a unique identification to each component to reduce the possibility of misdirected messages and provides the protocols to be used by the components reducing the chance of garbled messages. The two components trade configuration data prior to communicating to ensure that they have the correct party.

Abstract: Safety level error detection comparable to that provided by redundant wired safety relays is obtained on a backplane of a programmable logic controller or the like by a combination of error detection methods that in sum provide the requisite level of error detection required without necessitating a particular hardware requirement or duplicative message transmissions.

Abstract: A highly reliable industrial control system is produced by opening multiple connections on a connected messaging network running a standard serial protocol. The two connections are used to transmit redundant data and include a reply message to the message producer. Errors in the messages or media failure may be detected using standard error detection codes, retry counters and deadman timers. Comparison of the data of the two messages can reveal other types of failure not apparent by these former techniques.

Abstract: Error detection codes implemented in standard network interface circuits are enlisted in obtaining high reliability necessary for safety systems by virtual testing of the network interface circuits using background levels of network errors. The frequency of the testing matches the frequency of the network errors.

Abstract: A highly reliable industrial control system is produced using a network running a standard serial protocol on two redundant messages. A safety protocol is embedded within the standard serial protocol by adding to special error detecting data redundant with the protocol of the standard serial network. In addition, only a single network protocol module (CAN) is necessary to transfer two logical messages of data between modules. In order to still provide redundancy, the data on one of the messages is encoded in a predetermined manner, such as by inverting each bit of data, prior to transmission over the network. The data is then decoded at the destination module and compared to the data on the other logical message to determine whether a transmission error has occurred. Safety protocol may be implemented in an additional level for integrated circuits or through firmware changes in programmable aspects of the industrial controller components.

Abstract: A bridge usable in a highly reliable industrial control system provides an interface between a producer module transmitting redundant messages in accordance with a communication protocol and a consumer module receiving the messages in accordance with a different communication protocol. The bridge includes a first network interface receiving two messages from the producer, a microprocessor capable of converting the messages from the producer communication protocol to consumer communication protocol, and a second network interface transmitting the messages to the consumer. One of the messages is reversible altered with respect to the other message. The altered message is uninverted in the consumer module, and compared to the other message to ensure that no transmission errors have occurred.

Abstract: An autonomous Web server may be connected to an industrial control system to provide direct access to input and output points through connections between the Web server and the input and output points. Coordination with the programmable logic controller is implemented through a set of lock flags which prevent conflicts either between multiple Web connections or between Web connections and the control produced by the programmable logic controller.

Abstract: A highly reliable industrial controller uses low complexity field programmable gate-arrays (FPGA) in lieu of standard microprocessors where each FPGA is programmed so as to provide for a different internal implementation of the control program as a set of interconnected logical gates. Variations in the outputs of the FPGAs caused by hardware failure may be corrected by choosing the most common output, a default output or a default value. Errors may be detected though conventional hardware error detection methods or by a direct comparison of the outputs which under normal conditions should match each other.

Abstract: An industrial control system uses a number of autonomous control units, each associated with one piece of equipment in an industrial process. The autonomous control units negotiate by bidding among themselves to determine a common set of input and output values for the interconnected machines with which they are associated. Each autonomous control unit determines whether input values are acceptable by using a model of its associated equipment. The model provides anticipated output values which may be compared against a predetermined range of outputs of associated machines, outputs compatible with downstream machines, or the constraints of the overall industrial process according to a designated job to be accomplished. Optimization of the input and output values is provided by allowing preliminary bids to be the subject of optimizing counter-bids if the original bid value could have been accepted.

Abstract: An industrial control system uses a number of autonomous control units, each associated with one piece of equipment in an industrial process. The autonomous control units negotiate by bidding among themselves to determine a common set of input and output values for the interconnected machines with which they are associated. Each autonomous control unit determines whether input values are acceptable by using a model of its associated equipment. The model provides anticipated output values based on given input values and is effectively operated in reverse for external counterbids proposing output values and needing to know input values, or internal counterbids seeking to optimize counterbid input values against output based goals. The reverse modeling iteratively applies inputs to the model until the desired output is attained. The inputs may be constrained by predefined intermediate constraints and may be changed in a binary search pattern. In multi-input models, one input may be specified for iteration.

Abstract: A rolling mill system uses a number of autonomous control units, each associated with one piece of equipment of the rolling mill system. The autonomious control units include data indicating not only their constraints of operation, but also reflecting the constraints of operation of machines to which they are attached and with which they share common operating parameters. An autonomous control unit associated with a machine having operating parameters in common with another machine of the rolling mill system adopts the intersection of the ranges of the machine constraints of the two machines. Machine constraints are preserved to the extent possible as ranges, so as to permit flexibility in selecting and seeking goals by the individual autonomous control units.

Abstract: An industrial control system uses a number of autonomous control units, each associated with one piece of equipment in an industrial process. The autonomous control units include data indicating not only their constraints of operation but also reflecting the constraints of operation of machines to which they are attached and with which they share common operating parameters. An autonomous controller associated with a machine having operating parameters in common with another machine adopts the intersection of the ranges of the machine constraint of the two machines. Machine constraints are preserved to the extent possible as ranges so as to permit flexibility in selecting and seeking goals by the individual autonomous control units.

Abstract: A rolling mill system associates an autonomous control unit with each piece of equipment in the rolling mill system. The autonomous control unit has a model of the particular piece of equipment, for example, of the rolling mill, a reheat furnace or a cooling bath, and data indicating constraints on the operation of the equipment. A metal shape to be produced is described as a set of machine independent steps, and the performance of these steps is bid upon by the autonomous control units according to the constraint models and internal goals. Bids having conflicting requirements may generate counterbids until a complete plan for the production of the product is generated.

Abstract: A communication network for an industrial control system permits multiple masters and complex network topologies by transmitting data as packets through paths of nodes on the networks. The packets containing data are preceded by an OPEN message which pre-configured each node with the necessary information to process the stream of succeeding packets in an efficient manner and thus to reduce the necessary overhead in the transmission of each data packet. Each node receiving the OPEN message evaluates its resources and if those resources are insufficient to reliably handle the indicated packets, a message is returned to the originating node indicating that a connection cannot be formed.