Abstract: A field device includes process communication circuitry configured to communicate in accordance with a process communication protocol. A controller is coupled to the process communication circuitry. The controller includes timing circuitry and is configured to generate periodic time signals during an operational period of the field device and store an indication of operational time based on the periodic time signals in non-volatile memory. The controller is configured to employ the process communication circuitry to provide an indication of operational time to a remote device.

Abstract: A field device includes process communication circuitry configured to communicate in accordance with a process communication protocol. A controller is coupled to the process communication circuitry. The controller includes timing circuitry and is configured to generate periodic time signals during an operational period of the field device and store an indication of operational time based on the periodic time signals in non-volatile memory. The controller is configured to employ the process communication circuitry to provide an indication of operational time to a remote device.

Abstract: A process variable transmitter which has a manual adjustment for span and zero or the like. The adjustment has a finer adjustment range where the output changes responsive to changes in the position of the adjustment. The adjustment has a coarse range where the transmitter output changes automatically as a function of time to provide coarser adjustment. An operator can move the back and forth between the adjustment ranges until a desired output value is observed. When adjustment is complete, the operator can manually select the desired transmitter output value and then a selection circuit stores the setting in non-volatile memory. After a setting is stored, the transmitter output is not sensitive to movement of the manual adjustment, but is instead controlled by the stored setting.

Abstract: A charge balanced feedback type transmitter generates charge packets representative of a sensed parameter. Improved performance is achieved by the additiion of resistance connected between a charge packet generating reactance and an integrator to reduce the effects of noise caused by switching transients and by ground noise which is coupled to the charge packet generating circuitry by stray capacitance. The charge packets are integrated by the integrater, and the integrator output is supplied from a selective basis to the input of a comparator. The output of the comparator is used to control the application of charge packets to the integrator to achieve charge balance. The input of the comparator is selectively connected to the output of the integrator, to a first supply voltage, or to a second supply voltage to ensure a stable output of the comparator at a critical time when charge is being supplied to the integrator.

Abstract: An industrial process control transmitter has a modular construction, with a detector module and an output module electrically connected together by a serial bus. The output module includes a microcomputer, a modem for digital communication over the two-wire loop, analog output circuitry for controlling loop current, a digital-to-analog converter, and a memory for storing calibration factors and D/A characterization factors.The detector module includes several sensors with associated circuitry to convert the sensor signals to digital signals. The detector module also includes a memory which contains characterization factors unique to the sensors which can be used by the microcomputer to correct the digital values provided by the detector circuitry. The microcomputer of the output module is considered the master unit, and all of the circuits of the detector board which interface with the serial bus are considered slave units.