Abstract: A redundant fieldbus redundant system includes two independent conditioned power modules which automatically detect cable faults, such as short or open circuits on both the host and field sides of the network. The power modules are interfaced directly on one side to the primary and backup H1 cards of the host system, and are directly interfaced on the other side to an automatically terminating network device coupler module which provides connections to field devices. The redundant fieldbus system provides power and communications in a parallel physical configuration between the host system and the field devices irrespective of any single point failure in the network. In case of a fault, the redundant fieldbus system automatically eliminates the faulty section of the network, switches power and communications to the healthy portion of the network and terminates the network for signal integrity.

Abstract: A redundant fieldbus system provides power and communications in a parallel physical configuration between the host system and attached field devices irrespective of any single point failure in the network. In case of a fault, the redundant fieldbus system automatically eliminates the faulty section of the network, switches power and communications to the healthy portion of the network and terminates the network for signal integrity. A device coupler for the system may include a fault detector coupled to an auto-termination circuit that terminates a fieldbus cable when a fault is detected. The device coupler may include fault detection and isolation coupled to each set of spur terminals used to connect field devices to the device coupler. A field device for the system may include circuitry for deselecting a faulty cable while maintaining connection to a healthy cable.

Abstract: A power supply adapted to provide power for one or more field devices over a protocol bus based network, such as a fieldbus network, which includes an oscillator circuit and a power control switch mounted at the output of a conditioned power supply. The oscillator circuit is adapted to detect a cable fault such as a short circuit. When a cable fault is detected, the oscillator circuit sends a signal to the power control switch to stop the power supply from feeding current to the network and to activate an alarm signal to alert a host of the cable fault.

Abstract: A redundant fieldbus redundant system includes two independent conditioned power modules which automatically detect cable faults, such as short or open circuits on both the host and field sides of the network. The power modules are interfaced directly on one side to the primary and backup H1 cards of the host system, and are directly interfaced on the other side to an automatically terminating network device coupler module which provides connections to field devices. The redundant fieldbus system provides power and communications in a parallel physical configuration between the host system and the field devices irrespective of any single point failure in the network. In case of a fault, the redundant fieldbus system automatically eliminates the faulty section of the network, switches power and communications to the healthy portion of the network and terminates the network for signal integrity.

Abstract: A redundant fieldbus system provides power and communications in a parallel physical configuration between the host system and attached field devices irrespective of any single point failure in the network. In case of a fault, the redundant fieldbus system automatically eliminates the faulty section of the network, switches power and communications to the healthy portion of the network and terminates the network for signal integrity. A device coupler for the system may include a fault detector coupled to an auto-termination circuit that terminates a fieldbus cable when a fault is detected. The device coupler may include fault detection and isolation coupled to each set of spur terminals used to connect field devices to the device coupler. A field device for the system may include circuitry for deselecting a faulty cable while maintaining connection to a healthy cable.

Abstract: An electronic circuit for terminating a plurality of conductors at a node of a network, including means to detect current flowing through one of the conductors and means to switch between a continuing circuit, whereby continuity of the network is maintained, on detecting current above a first predetermined threshold, and a terminating circuit, whereby the network is terminated with an appropriate terminating circuit, upon detection of current at, or below, a second predetermined threshold.

Abstract: A system and method is disclosed for synchronizing clocks in a plurality of devices connected by a communication channel. A master control device is coupled to one or more slave control devices, e.g., event recorders, across a communication channel. Preferably, the communication channel is implemented according to an RS-485 interface. By periodically interrogating and monitoring the responses of each of the slave control devices, the master control device determines the transit time, i.e., communication, delays to each of the slave control devices. Operating in conjunction with this data, the master control device can then interpret and/or adjust any event times reported by the event recorders to improve the relative time accuracy of the event recorders as compared to a time maintained by the master control device. Consequently, the control system can achieve a relative time synchronization accuracy between the master and slave times to within 100 microseconds and preferably 100 nanoseconds or less.

Abstract: An electro-pneumatic control system and single op-amp PID control circuit is provided for regulating the output pressure response provided to a load. The control system includes a control valve for producing a control pressure signal and a booster for providing an output pressure response to a pneumatic load in accordance with the control pressure signal. A pressure sensor is further provided for measuring the output pressure response provided to the load and for generating a corresponding feedback voltage signal provided to the control circuit. The control circuit compares the feedback signal to a command signal input in accordance with a predetermined transfer function having proportional, integral and derivative (PID) components, and generates a control voltage signal for stably controlling the output pressure response provided to the load.

Abstract: A microprocessor-controlled remote resistance measurement system is disclosed wherein the connection leads to the three- or four-wire resistance temperature devices (RTDs) are multiplexed via a four-channel analog multiplexer at the input of the unit. A separate two-channel multiplexer is also used to multiplex a fifth input for measurement of a reference resistor. The output of the multiplexer is coupled to a voltage-to-frequency converter, wherein the frequency output is utilized as an input to the microprocessor-based controller. The microcontroller can check for broken wires by addressing the multiplexers to individually isolate any of the connecting wires to the remote RTD sensors. The output of the multiplexer is monitored in a Test Mode by connecting a known impedance to the multiplexer output to determine if any RTD connections are defective.

Abstract: A multipoint communications system for transmitting the values of a multiplicity of analog parameters from one point digitally to another point and reconverting then into analog parameters. The system includes a plurality of input modules which communicate with respective output modules over a communications link. The input and output modules are configured similarly with a control processor connected to either multiplexing circuitry, in the case of an input module, or demultiplexing circuitry in the case of an output module. The multiplexing circuitry is connected to a plurality of configurable input circuits which receive the values of the various measured conditions or parameters. The demultiplexing circuitry is connected to a plurality of configurable output circuits which output the values of the various measured conditions or parameters. In a preferred protocol, a link master is chosen from among the input modules to generate a polling sequence for the input-output module pairs.

Abstract: An annunciation system for a wireless weighing system. The weighing system includes control keys for selecting and displaying the weights from a plurality of remote weighing pads, each having a separate through the air communications channel. The weighing system further provides a mode for storing a zero value for each pad. In the preferred embodiment, the annuniciation system comprises a plurality of LED combinations where each combination is located proximately to a corresponding pad select key which indicates a particular communications channel. Each LED combination has a plurality of states including off, green, red and amber which indicates a condition of the corresponding communications channel. Additionally, each LED combination can indicate a condition of a corresponding communications channel by being off, on steady, or blinking.

Abstract: A wireless weighing system for determining the weight of each wheel of a vehicle and for combinations and percentages thereof. Wheel weighing pads are placed under respective wheels of the vehicle and each contains a load cell whose analog output is converted to a digital value which can be transmitted to a central control. The communications technique uses infra-red radiation and a digital protocol which allows the central control to interrogate each individual weighing pad and receive a weight response without interference. The interrogation signal of the central control comprises a series of pulse envelopes containing high intensity IR pulses of a short duration where the duration of the envelope and position in the sequence indicates an address of a respective wheel pad.

Abstract: A housing for an electrical circuit is to be releasably mounted in an explosion-proof box without modifying the structure of the box. The housing is provided with at least one spring which extends away from the housing into engagement with an inner surface of the box. This engagement between the spring and the inner surface of the box deflects the spring, exerting force on the housing in such a way as to resiliently hold the housing inside the box.

Abstract: A two-wire frequency to DC converter utilizes a multistage binary counter which is controlled by a crystal oscillator and the input frequency. This arrangement provides precisely shaped square wave pulses at the output of the counter whose frequency is functionally related to the input frequency and which can be fed into a low pass filter to obtain an average DC value for the AC input. The output terminal at each stage of the binary counter has a plurality of open terminals, each associated with a particular frequency. By connecting a single diode across a selected open terminal, the converter which is constructed without regard to any input frequency, so it can be mass-produced, can be easily customized for a particular input frequency range.

Abstract: A plurality of spaced parallel guides are mounted on a support. The edges of printed circuit boards are mounted in these guides. The printed circuit boards are formed with the male portion of an electrical connector at one end and a locking and regulating plunger at the opposite end.The support is provided with the female portion of an electrical connector which is positioned so that when the edges of the printed circuit board are mounted in the guides, the male part of the connector is aligned with the female connector whereby the male connector can penetrate the female connector. The plunger both locks the printed circuit board on the rack and regulates the depth of penetration of the male connector into the female connector.

Abstract: This invention relates to a pressure transducer and more particularly to a pressure transducer having means by which the pressure transducer can be removed from a pressurized line without loss of line pressure. The pressure transducer is mounted in a housing, which is adapted to be releasably mounted on a bracket. The bracket is provided with a tubular needle valve coupling which is adapted to be connected to a pressurized line. The coupling normally keeps the pressurized line closed, but when the housing of the pressure transducer is mounted on the bracket, the needle valve in the coupling is automatically actuated, opening the pressure transducer to the pressure in the line.