Abstract: A pressure sensor is disclosed for measuring the pressure of a fluid, the pressure sensor comprising an atmospheric pressure sensing element, a fluid pressure sensing element, a processing unit, and a switch. The atmospheric pressure sensing element measures atmospheric pressure and the fluid pressure sensing element measures relative pressure of the fluid with respect to the atmospheric pressure. The switch is electrically coupled to the processing unit and comprises a first state and a second state, wherein: when the switch is set to the first state, the processing unit determines the absolute pressure of the fluid, and the processing unit generates an output corresponding to the absolute pressure of the fluid; and when the switch is set to the second state, the processing unit determines the relative pressure of the fluid, and the processing unit generates an output corresponding to the relative of the fluid.

Abstract: An atmospheric pressure sensor is disclosed which comprises an atmospheric pressure sensing element, a processing unit, and an interface unit. The atmospheric pressure sensing element is operable to measure the atmospheric pressure, and the processing unit is electrically coupled to the atmospheric pressure sensing element and is operable to read the measured atmospheric pressure from the atmospheric pressure sensing element. The processing unit is operable to generate a message if the measured atmospheric pressure meets one or more criteria. And the interface unit is electrically coupled to the processing unit and is operable to electrically receive the message from the processing unit and transmit the message to a receiving device.

Abstract: A melt pressure sensor comprises a housing, a stem, a pressure sensing element, a time-to-digital converter, a processor, a digital-to-analog converter, and a first input. The stem comprises a pressure sensing surface fluidly coupled to a molten material. The pressure sensing surface is mechanically or fluidly coupled to the pressure sensing element, and the pressure sensing element is electrically coupled to the time-to-digital converter, which determines the melt pressure by measuring an electrical characteristic of the pressure sensing element. The processor reads the pressure from the time-to-digital converter and outputs an analog output value from the digital-to-analog converter representative of the melt pressure. When the first input is activated, the processor causes the analog output signal to have a predetermined value.

Abstract: A method and apparatus for verification of the linear position of a machine element driven by a motor is provided. The actual position of the element is detected and compared to an expected position. When the two positions differ from each other by more than a predetermined tolerance value for a predetermined amount of time, an error signal is generated which deactivates the motor and generates an alarm for the machine operator. Preferably, the linear position of the axis is detected by a transducer and the expected position is determined by detecting the rotary position of the motor through the use of a resolver, which is then converted to a linear equivalent through the use of the gearing ratio. The method and apparatus can detect faulty machine conditions and thereby prevent machine malfunction and/or machine damage. Preferably, the method and apparatus are used to verify the position of machine elements in an injection molding machine.

Abstract: A method and apparatus are provided for servo control of injection molding machine devices. A signal processor periodically produces analogue control signals for controlling machine mechanisms at a first loop closure interval and periodically produces digital control signals for controlling energization of machine heaters at a second loop closure interval. Values of analogue and digital control signals are determined according to control algorithms relating set point values and measured parameter values. Calculation of values of analogue control signals includes calculation of a first command value according to a first control algorithm, calculation of a second command value according to a second control algorithm and selection of the lesser of the first and second command values. Compensation for "cold" thermocouple junctions created at the connection of remote temperature sensing thermocouple leads and the signal processor interface circuits is provided.

Abstract: A transducer interface circuit is provided having means for detecting loss of connection of a transducer to the interface circuit. The interface circuit is intended for use with a transducer providing an output between two electrical poles of opposite polarity. Differential inputs of a differential amplifier are connected to the transducer poles. A bias current source is provided proximate the amplifier at least at one input, and the other input is connected to ground. Loss of connection between the transducer and amplifier results in saturation of the amplifier output.