Abstract: A circuit for compensating a silicon strain gauge pressure transmitter. The circuit includes: a current source, an embodiment of which may include an amplifying device and means for supplying the current source with an electric potential, a strain gauge bridge, a plurality of resistances that includes a feedback resistance, a series resistance, a current sampling resistance, and a load with parameters. The key to this invention is to add a series resistance and a feedback resistance to the circuit which eliminates the need for R.sub.c, the current sample resistor, to be a thermistor, and increases the operating temperature range of the sensor by compensating the sensor's parameter variations with temperature.

Abstract: A method and apparatus are described for using a computer to compensate for zero point and span errors as well as other non-linearities in the operation of strain gauge transducers. The apparatus comprises a semiconductor strain gauge transducer with a quasi stable voltage supply, two strain gauges and two precision resistors which form a voltage divider network; a scanner for scanning the strain gauges and precision resistors; an analog-to-digital converter for digitizing the output of the scanner; and a microprocessor for calculating a corrected output representing the phenomenon that is monitored by the strain gauge transducer. The microcomputer contains a memory in which are stored a set of bridge completion constants, a table of correction constants and a set of temperature compensation and signal conditioning algorithms.

Abstract: A microprocessor-based keyboard/display is described in which the function of the keys can be varied automatically depending on the instrument to which the keyboard/display is connected. The keyboard/display comprises a microprocessor, a read only memory in which is stored an operating program for the microprocessor, a keyboard having a plurality of keys, a display, and means for connecting said microprocessor to another instrument. In accordance with the invention, the program stored in said read only memory is responsive to a signal from the instrument to which said keyboard/display is connected whereby upon receipt of a signal from one type of instrument at said keyboard/display at least some of said keys of said keyboard are given first functions and upon receipt of a signal from a second type of instrument said keys are given different functions.

Abstract: A microprocessor based single loop control instrument is described which can operate as any one of several different types of controllers, each of which can provide two or more different modes of operation. The control instrument comprises a microprocessor, a read only memory in which is stored the operating program for the control instrument, means for causing the control instrument to operate as one of the types of controllers provided for by a program stored in the read only memory and means for selecting the mode of operation of the controller. Further, in accordance with the invention, the control instrument is supplied with a control panel controlled by a second microprocessor and connected to the first microprocessor by a communication bus. The second microprocessor controls a bar graph display for displaying at least one signal related to the operation of the control instrument as well as means for selecting the signal that is displayed.

Abstract: A switched frequency divider is disclosed comprising an array of bistable devices which are linked together so as to propagate through the array a low or high signal applied to an input to the array, first gating means for inserting at least one more bistable device into the array, and second gating means for making such an insertion only when the output of the array completes a cycle. To provide for an output wave form that has approximately a 50 percent duty cycle, the bistable devices are coupled togther in the form of a Johnson counter. To permit a change in the divisor only upon the completion of an output cycle, the second gating means is a bistable device which reads an incoming control signal only when the output of the Johnson counter makes a specified change in state. Advantageously, the switched frequency divider may be used as an FSK modulator to generate different AC frequencies from a single AC input signal in response to a digital data signal applied to the divider as said control signal.

Abstract: A method and apparatus are described for improving the printing speed of a dot matrix printer. The printer comprises a conventional array of printing elements and a printing element addressing matrix comprising a set of address lines and a set of strobe lines. Each printing element is connected in series between one of the address lines and one of the strobe lines. Each address line is connected to the output of a first register, and each strobe line to the output of a second register.