Abstract:
In this invention, a multivariable transmitter (2) providing an output representative of mass flow has a dual microprocessor structure. The first microprocessor (72) compensates digitized process variables and the second microprocessor (80) computes the mass flow as well as arbitrating communications between the transmitter (2) and a master (88).
Abstract:
A charge balanced feedback type transmitter (10) generates charge packets representative of a sensed parameter. Improved performance is achieved by the addition of resistance (R1), (R2) connected between a charge packet generating reactance (C1), (C2), (CL1), (CL2) and an integrator (30) to reduce the effects of noise caused by switching transients and by ground noise which is coupled to the charge packet generating circuitry (12) by stray capacitance. The charge packets are integrated by the integrator (30), and the integrator output is supplied from a selective basis to the input of a comparator (32). The output of the comparator (32) is used to control the application of balance. The input of the comparator (32) is selectively connected to the output of the integrator (30), to a first supply voltage, or to a second supply voltage to ensure a stable output of the comparator (32) at a critical time when charge is being supplied to the integrator (30).
Abstract:
A field device includes a power control module, a network interface module that communicates over a wireless network, and a device interface module for operating transducers, such as a sensor or an actuator. The power control module controls distribution of electrical power so that the network interface module receives electrical power while it is attempting to join the wireless network. Once the network interface module has joined the wireless network, the power control module allows the network interface module and the device interface module to share electrical power.
Abstract:
A smart field-mounted control unit (22), for controlling a process, receives signals and sends a command output over a two-wire circuit (18) which powers the control unit (22). An input section (50) receives the signals, which can be instructions representative of commands or instruction sets, process variables sensed by external control units or setpoints representative of a desired process state. The instructions are representative of a control requirement of the process and adjust a controlling section (52) in the control unit (22) to generate the command output (58) in conformance with the control requirement. The command output (58) can be a function of the difference between the process setpoint and a process variable, or a function of a linear combination of a process variable and its calculated time integral and time derivative functions. A sensing section (100) in the control unit (22) can sense and scale a process variable for generating the command output (58) as well. The control unit (22) can include a regulator section, controlled by the command output (58), which regulates application of a mechanical, hydraulic, pneumatic or electromagnetic force applied to the process.
Abstract:
A process variable transmitter (100) for use with a removable operator interface (202) has a non-volatile memory (204) and a latching component (210). The non-volatile memory (204) stores device settings (206). The latching component (210) prohibits changes to transmitter settings if the removable operator interface (202) is absent. Circuitry in the transmitter (100) detects the presence of the removable operator interface (202). The removable operator interface (202) can include zero and span settings.
Abstract:
A field device (14) for use in an industrial process control or monitoring system (10) includes terminals (56H, 56L) configured to connect to a two-wire process control loop (16) configured to carry data and to provide power. In one embodiment, RF circuitry (22) in the field device (14) is configured for radio frequency communication having variable power consumption. In another embodiment, the RF circuitry (22) is coupled to the field device (14) through a separate digital communication bus (100) . A method of modulating the power of RF communication based upon a process communication signal is also provided.
Abstract:
A pressure transmitter assembly (106) for measuring a pressure of a process fluid (104) includes an isolation diaphragm assembly (120). A pressure sensor (130) is spaced apart from the isolation diaphragm assembly (120) to provide thermal isolation. A conduit (122) extends from the isolation diaphragm assembly (120) to the pressure sensor (130) and is configured to carry isolation fill fluid.
Abstract:
A transmitter (10) for use in a process control system has externally accessible actuators for permitting adjustment of the zero and span (or full scale) settings of the transmitter (10). The transmitter (10) has an explosion-proof housing (12) which includes an interior chamber (14, 16) in which transmitter circuitry is located. Each of the actuators includes a movable magnet (52A, 52B) which operates a magnetic reed switch (62A, 62B) located within the interior chamber (14) of the housing (12) through a wall (17) of the housing (12). By moving the magnet (52A, 52B) the corresponding reed switch (62A, 62B) can be changed from a non-actuated to an actuated state. When the zero reed switch (62A) is actuated, the transmitter circuitry adjusts its output so that the present value of the parameter represents a process zero. When the span reed switch (62B) is actuated, the transmitter circuitry adjusts its output so that the present value of the sensed parameter represents a process maximum.
Abstract:
A wireless field device (102) for use in controlling or monitoring an industrial process (100), includes a process interface (110) configured to couple to a process fluid. Field device circuitry is coupled to the process interface (110) and configured to measure or control a process variable. Wireless communication circuitry (154) is configured to provide wireless communication. At least one electrical access terminal is configured to provide an electrical connection to circuitry of the field device. A power supply (160) is configured to power the wireless field device. The power supply (160) includes a removable primary power source (162) to provide power to the field device (102) for extended periods of time. A secondary power source (164) is configured to provide power to the field device (102) when the primary power source (162) is removed.
Abstract:
An adapter (300) for coupling to a process control transmitter (308) of the type used to monitor a process variable in an industrial process includes a first connection configured to couple to a first side of a two wire process control loop (302), a second connection configured to couple to a second side of the two wire process control loop (302) and in series with a first connection to a process control transmitter (308), and a third connection configured to couple to a second connection of the process control transmitter (308). Wireless communication circuitry is coupled to at least the third connection and is configured to provide wireless communication for the process control transmitter (308). Intrinsic safety circuitry (460) coupled to at least one of the first, second and third connections is configured to limit transfer of electrical energy to a value which is less than an intrinsic safety value.