Abstract: A two-wire field-mounted process device with multiple isolated channels includes a channel that can be an input channel or an output channel. The given input or output channel can couple to multiple sensors or actuators, respectively. The process device is wholly powered by the two-wire process control loop. The process device includes a controller adapted to measure one or more characteristics of sensors coupled to an input channel and to control actuators coupled to an output channel. The controller can be further adapted to execute a user generated control algorithm relating process input information with process output commands. The process device also includes a loop communicator that is adapted to communicate over the two-wire loop.

Abstract: A two-wire field-mounted process device with multiple isolated channels includes a channel that can be an input channel or an output channel. The given input or output channel can couple to multiple sensors or actuators, respectively. The process device is wholly powered by the two-wire process control loop. The process device includes a controller adapted to measure one or more characteristics of sensors coupled to an input channel and to control actuators coupled to an output channel. The controller can be further adapted to execute a user generated control algorithm relating process input information with process output commands. The process device also includes a loop communicator that is adapted to communicate over the two-wire loop.

Abstract: A two-wire field-mounted process device with multiple isolated channels includes a channel that can be an input channel or an output channel. The given input or output channel can couple to multiple sensors or actuators, respectively. The process device is wholly powered by the two-wire process control loop. The process device includes a controller adapted to measure one or more characteristics of sensors coupled to an input channel and to control actuators coupled to an output channel. The controller can be further adapted to execute a user generated control algorithm relating process input information with process output commands. The process device also includes a loop communicator that is adapted to communicate over the two-wire loop.

Abstract: A two-wire field-mounted process device with multiple isolated channels includes a channel that can be an input channel or an output channel. The given input or output channel can couple to multiple sensors or actuators, respectively. The process device is wholly powered by the two-wire process control loop. The process device includes a controller adapted to measure one or more characteristics of sensors coupled to an input channel and to control actuators coupled to an output channel. The controller can be further adapted to execute a user generated control algorithm relating process input information with process output commands. The process device also includes a loop communicator that is adapted to communicate over the two-wire loop.

Abstract: A two-wire field-mounted process device with multiple isolated channels includes a channel that can be an input channel or an output channel. The given input or output channel can couple to multiple sensors or actuators, respectively. The process device is wholly powered by the two-wire process control loop. The process device includes a controller adapted to measure one or more characteristics of sensors coupled to an input channel and to control actuators coupled to an output channel. The controller can be further adapted to execute a user generated control algorithm relating process input information with process output commands. The process device also includes a loop communicator that is adapted to communicate over the two-wire loop.

Abstract: A two-wire temperature transmitter performs thermocouple diagnostics on a thermocouple attached to the transmitter to determine if, and the extent to which, the thermocouple has degraded. Various methods of obtaining thermocouple resistance are also provided.

Abstract: A process fluid temperature transmitter includes circuitry that improves compensation of error due to the presence of one or more non-associated voltage sources in a resistance temperature device (RTD) circuit. A method of compensating for such error is also provided.

Abstract: A transmitter in a process control loop measures temperature. A calibrator includes a known calibration element which is connected to the transmitter. Software in the transmitter compares a measured value of the calibration element with the actual value of the calibration element and responsively calibrates the transmitter. The calibrator includes a temperature calibration sensor for coupling to a terminal block of the transmitter. The temperature calibration sensor provides an actual temperature input to the transmitter. The transmitter measures actual temperature of the terminal block and compares actual temperature with a temperature measured by an internal terminal block temperature sensor, and responsively calibrates the internal temperature sensor.

Abstract: A transmitter in a process control loop measures temperature. A calibrator includes a known calibration element which is connected to the transmitter. Software in the transmitter compares a measured value of the calibration element with the actual value of the calibration element and responsively calibrates the transmitter. The calibrator includes a temperature calibration sensor for coupling to a terminal block of the transmitter. The temperature calibration sensor provides an actual temperature input to the transmitter. The transmitter measures actual temperature of the terminal block and compares actual temperature with a temperature measured by an internal terminal block temperature sensor, and responsively calibrates the internal temperature sensor.

Abstract: A temperature transmitter in a process control system includes a temperature sensor which senses temperature and provides a sensor output related to sensed temperature. An analog-to-digital converter coupled to the sensor output provides a digitized output related to the sensor output. A microprocessor receives the digitized output, compensates the digitized output and provides a temperature output. Comparison circuitry compares the sensor output to a first threshold and provides an inhibit signal to the microprocessor if the sensor is outside of the first threshold.

Abstract: A transmitter in a process control loop measures temperature. A calibrator includes a known calibration element which is connected to the transmitter. Software in the transmitter compares a measured value of the calibration element with the actual value of the calibration element and responsively calibrates the transmitter. The calibrator includes a temperature calibration sensor for coupling to a terminal block of the transmitter. The temperature calibration sensor provides an actual temperature input to the transmitter. The transmitter measures actual temperature of the terminal block and compares actual temperature with a temperature measured by an internal terminal block temperature sensor, and responsively calibrates the internal temperature sensor.

Abstract: A transmitter transmitting a sensed process variable over a conductor includes a cylindrical housing having a terminal compartment and an electronics compartment separated by a bulkhead. The terminal compartment used for conductor connection is subject to moisture accumulation. An access channel fully intersects an internal surface of terminal compartment such that the access channel drains moisture from the terminal compartment across a range of mounting orientations. The transmitter includes a circuit in the electronics compartment for compensating a process variable and providing the compensated process variable via a feedthrough circuit assembly in the bulkhead, which in one embodiment, includes an encapsulated radio frequency interference filter, to terminals in the terminal compartment for coupling to a conductor that is connected to an external controller.

Abstract: An air data sensor device, such as a pitot, total air temperature sensor, etc., includes an elongated probe having a sensor therein for sensing air flow parameters and a strut for positioning the probe in a desired position on an air vehicle. To avoid ice build-up on the device causing erroneous sensing of air flow parameters a substantially constant wattage electric resistive heater is provided in the probe for deicing. A PTC (positive temperature coefficient) resistive heater is disposed in the support at a location thermally isolated from the probe heater but in thermally conductive relationship to the external surface of the support. The PTC heater is connected in series with the probe heater and continuously varies heater power in response to the rate of heat dissipation at the external surface of the sensor device thereby preventing burn-out of the probe heater and erosion of the probe.

Abstract: A positive temperature coefficient (PTC) resistance heater assembly is used in combination with an angle of attack vane to provide automatic means for maintaining the temperature of the vane at a level which will de-ice the vane. The heater assembly is embedded in a recess in the vane and is made up of a plurality of individual PTC resistors connected electrically and mechanically in parallel by flexible electrically conductive perforated strips which permit the individual resistors to move relative to each the other under thermal stress and which also permit the encapsulation of the resistors in a suitable thermally conductive, electrically oinsulative material that is sufficiently resilient to permit the individual resistors to expand and contract relative to the vane during use.