Fisher Controls International LLC

Harry A Burns

Brent Hans Larson

Larry Keith Brown

Larry K Brown

A method for providing an indication and alarm of a possible failure in a fluid control valve stem, plug or seat in a process control system having a microprocessor based valve positioner. The drive pressure, drive signal and valve position feedback are monitored. If greater than a predetermined change in the drive pressure or the valve position feedback is detected, then a second series of detection steps is initiated. In the second detection steps the present set point to process value relationship, such as flow rate or other process variable is compared to a stored test cycle derived set point to process value relationship for the same set point. If there is a process value change, then the operator is alerted as this change may indicate there is a damaged valve stem, plug, or seat problem which needs to be inspected.

Method for detecting broken valve stem

A maintenance interface device for use in a digital, loop-powered process control network includes an interface to either a two-wire input/output port of a field device or to a two-wire communication media, a control logic for determining a simple status of the field device or communication loop, and a display for displaying the simple status. The maintenance interface device may be used for fault analysis to detect whether a field device or a communication loop is operational or nonoperational, powered or unpowered, and generating a valid communication signal or generating an invalid communication signal. The maintenance interface device is adapted to perform simple functionality tests on a plurality of devices in a process control network including a loop controller, a digital control system, an operator console, a workstation, a personal computer, and a bridge to thereby detect the functionality of those devices on a communication wire. The maintenance interface device is self-powered, powered from the device under service, or powered from a communication media such as a bus.

Maintenance interface device for a use in a process control network

The present invention is directed to a method of and a device for monitoring, from a central location, the current operating conditions (such as values of process parameters) in a process control network having distributed control functions. In one embodiment, the method and device of the present invention use scheduled periodic communications to send signals containing, for example, measured values of process parameters developed by field devices to a centralized viewing device. The viewing device receives the signals and stores at least one value of the process parameters, and maybe more values if necessary to monitor and control the process. To retrieve the stored process parameters for viewing, the viewing device processes messages from human interface devices requesting the stored values of one or more of the stored parameters and then transmits response messages containing the stored values. The human interface device may be the same device as the viewing device, or may be a separate device that communicates with the viewing device using either the same or a different communication protocol as that used by the field devices to communicate with the viewing device. Additionally, the request and response messages may be sent between the devices using unscheduled queued communications.

Function block apparatus for viewing data in a process control system

An interface between a remote communications network and a process control system includes a storage device, a communication software stack and a user software layer. The user software layer enables interfacing between the remote communications network and the process control system by directing the communication software stack to operate in the process control system using a process communication protocol, by monitoring the message traffic on the communication software stack, and by copying requested message traffic to the storage device. The user software layer also includes media interface software that allows access to the storage device by the remote communications network to thereby deliver specific data to a device connected to the remote communications network.

Network accessible interface for a process control network

A schematic generator for use in a process control network, in which control functions are implemented by field devices interconnected at various and distributed locations on a bus, polls each of the field devices to retrieve information pertaining to the identity of the device, the identity of the control functions associated with the device, the manner in which the device communicates with other devices with respect to each of the control functions associated with that device, the timing associated with the execution of each of the control functions of that device and the timing of the communication activities associated with each of the control functions of that device. The schematic generator then analyses the retrieved data to identify the manner in which the devices are physically connected on the bus and the manner in which the different control functions are interconnected over the bus to perform process control loops within the process control network. Thereafter, the schematic generator creates one or more schematics, such a maintenance schematic illustrating the physical layout of the field devices in the process control network, a control loop schematic illustrating the interconnections between functions within one or more of the deceives that form a control loop, and a timing schematic illustrating the timing of or the amount of communications occurring on the bus.

Schematic generator for use in a process control network having

Process control network with redundant field devices and buses

Method and apparatus for debugging and tuning a process control network

A field device for use in a process control network having a plurality of devices communicatively coupled by a two-wire, all-digital communication bus includes a connector that connects the field device to the two-wire, all-digital bus to enable all-digital communication over the bus, a memory that stores a diagnostic test routine having a series of device or process diagnostic test instructions, and a controller that performs the device or process diagnostic test instructions stored in the memory to implement a device or process diagnostic test using the field device. A data collection unit within the field device collects diagnostic data generated during the diagnostic test and a communication unit communicates the collected diagnostic data over the bus to a host device for processing. The controller may include a program language interpreter adapted to interpret the diagnostic test instructions which may be provided to the field device from another one of the devices via the bus.

Local device and process diagnostics in a process control network having

A diagnostic system is adapted to perform device and process diagnostics in a process control network having a plurality of process control devices communicatively linked over a bus, wherein each of the devices is capable of preforming a process control function and of communicating over the bus using scheduled periodic communications. The diagnostic system is disposed in a first one of the devices and includes a signal generator that produces a diagnostic control signal, a communicator configured to deliver the diagnostic control signal to a second one of the devices using scheduled periodic communications, and an output signal receiver adapted to receive an output signal developed by the second device in response to the diagnostic control signal. The diagnostic system may use the received output signal to perform diagnostics or may send this signal to a host device for diagnostic analysis.

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Marshalltown, IA, United States of America

Harry A Burns