Abstract: A method for reducing thermal dissipation in a single PLC package includes implementing a pulse width modulated current regulator including a field effect transistor (FET) switch, and utilizing a turn on delay of the FET to provide a wide operating range of current. The FET has an inherent turn-on time delay that can be exploited such that, as the duty cycle is reduced, the FET's drain to source impedance dominates an inductive path of an output filter and increases output filtering.

Abstract: A control circuit for configuring at least one I/O module connector pin is provided. The circuit includes at least one port controlling a configuration of the at least one pin.

Abstract: The invention disclosed is useful in an I/O system of a programmable controller and provides a method and circuitry by which control and diagnostic information is exchanged between a control unit of an I/O module and a plurality of input/output points of the I/O module. A control signal is generated in the control unit in the form of sequential pulse frames such that the control information is defined by a series of pulse width modulated pulses. Each frame includes a no-pulse time period following the review of pulses to mark the end of a frame. Each I/O point receives a control signal of its own and generates a clock pulse in response to each pulse. The clock pulse initiates a sampling of the corresponding pulse and simultaneously initiates return of a diagnostic signal value to the central unit by implementation of firmware in a switch processor. Thus, the control signal provides for sampling of its own content and provides for a return of a diagnostic data bit for each control bit.

Abstract: An input/output (I/O) port designed for electrical interconnection with multiple similar ports includes an input read circuit, an output drive circuit, and a circuit to control the port for input or output mode by electrically disconnecting the output drive circuit from the port. Also included is a back drive current protection circuit placed in series in between an external I/O line and the input read and output drive circuits which blocks backdrive currents from other active processors when the processor that includes the protection circuit is in a powered down state while still allowing full input/output functionality in a powered up state.

Abstract: A control circuit for configuring at least one I/O module connector pin is provided. The circuit includes at least one port controlling a configuration of the at least one pin.

Abstract: A method for reducing thermal dissipation in a single PLC package includes implementing a pulse width modulated current regulator including a field effect transistor (FET) switch, and utilizing a turn on delay of the FET to provide a wide operating range of current. The FET has an inherent turn-on time delay that can be exploited such that, as the duty cycle is reduced, the FET's drain to source impedance dominates an inductive path of an output filter and increases output filtering.

Abstract: The invention disclosed is useful in an I/O system of a programmable controller and provides a method and circuitry by which control and diagnostic information is exchanged between a control unit of an I/O module and a plurality of input/output points of the I/O module. A control signal is generated in the control unit in the form of sequential pulse frames such that the control information is defined by a series of pulse width modulated pulses. Each frame includes a no-pulse time period following the review of pulses to mark the end of a frame. Each I/O point receives a control signal of its own and generates a clock pulse in response to each pulse. The clock pulse initiates a sampling of the corresponding pulse and simultaneously initiates return of a diagnostic signal value to the central unit. Thus, the control signal provides for sampling of its own content and provides for a return of a diagnostic data bit for each control bit.

Abstract: A combined input/output circuit is provided which is configurable either as in input circuit or an output circuit for use in a programmable controller. The input/output circuit includes apparatus which detects undesired overcurrent and overvoltage external conditions and adaptively protects itself from such conditions. The circuit includes a sensing circuit which is capable of sensing overcurrent conditions and detecting input data depending on the configuration of the input/output circuit. The inherent characteristics of a switching device used to configure the circuit in either an input or output state are used to detect overcurrent and to limit fault current.

Abstract: A threshold detection circuit is provided for determining when a data input signal exhibits an amplitude which exceeds a first programmable threshold level, is less than a second programmable threshold level or between the first and second levels. Respective scaling circuits scale down the data input signal and a line voltage signal which is supplied to the circuit to generate a scaled data input signal and a scaled line voltage signal. The threshold detection circuit scales the first and second threshold levels by a predetermined factor. The scaled data input signal is compared with the scaled first and second threshold levels. In response to this comparison, the output of the circuit assumes a first logic state when the data input signal exceeds the first threshold level and assumes a second logic state when the data input signal exhibits an amplitude less than the first threshold level. The comparison is repeated for the second threshold level.

Abstract: The invention disclosed is useful in an I/O system of a programmable controller and provides a method and circuitry by which control and diagnostic information is exchanged between a control unit of an I/O module and a plurality of input/output points thereof. A control signal is generated in the control unit in the form of sequential pulse frames such that the control information is defined by a series of pulse width modulated pulses. Each frame includes a no-pulse time period following the review of pulses to mark the end of a frame. Each I/O point receives a control signal of its own and generates a clock pulse in response to each pulse. The clock pulse initiates a sampling of the corresponding pulse and simultaneously initiates return of a diagnostic signal value to the central unit. Thus, the control signal provides for sampling of its own content and provides for a return of a diagnostic data bit for each control bit.

Abstract: A method is disclosed for determining the operability of a switching device controlling an electrical load and the status of the load as open, shorted, or normally connected, without disruption of the operative state of the load. The method includes the steps of: (1) commanding the switching device to switch the load to the opposite state for a momentary period less than required for an actual change of state; (2) measuring electrical responses as an indication of the operability of the switching device and the status of the load; and (3) repeating the momentary switch of the load for increasingly longer periods of time until the status of the load is determined or until the momentary time period reaches limiting time duration.

Abstract: Input/output circuitry is disclosed for use in an I/O system of a programmable controller. The circuitry is protected against overcurrents without the use of fuses or circuit breakers, and is automatically restored to normal operation following correction of an overload condition. Diagnostic signals are produced for monitoring the operating condition of the circuitry. The invention includes an insulated gate transistor (IGT) having a main current section carrying a majority of the load current and an emulation section which carries a fractional portion of the load current. The emulation section current tracks the total current at all times. A current sensor monitors the emulation section current and provides a signal representing the instantaneous load current. This signal is continuously compared with preselected reference levels to derive a set of diagnostic signals that are indicative of the operating condition of the circuit, and whether output loads are open or shorted, for example.

Abstract: The invention disclosed provides circuitry which is selectively operable either as an input point or as an output point in a programmable controller having multiple input and output points for exchanging signals between a central processing unit (CPU) of the controller and a process being controlled. Preferably, operation as an input point or as an output point is under control of the CPU. The invention includes a common input/output terminal for terminating both input and output devices; an input return terminal for terminating a return conductor from the input device; an output return terminal for terminating a return conductor from the output device; a preload resistor connected between the input/output terminal and the output return terminal so that a status signal is developed across the preload resistor indicating the status (generally, open or closed) of the input device; and an insulated gate transistor (IGT) connected between the input/output terminal and the input return terminal.

Abstract: The invention disclosed is a control system for controlling a pair of separately excited motors arranged such that each motor of the pair drives a separate wheel on a common axle of an electrically powered vehicle. The control system continuously and individually adjusts the field excitation of the drive motors so that torque and speed of the separate wheels are apportioned to the wheels as a function of the steering angle of the vehicle.

Abstract: An electromagnetic contactor is provided with a flux sensing device, preferably a Hall effect sensor, mounted in its magnetic circuit. The magnetic circuit includes an air gap within which the flux sensing device is mounted. The air gap can be adjusted to control the percent of magnetic flux impinging on the flux sensing device whereby a signal can be taken from the device indicative of the magnitude of flux in the magnetic circuit. The signal can be used to control electrical excitation of the contactor at a predetermined flux level.

Abstract: Apparatus disclosed for regulating a substantially constant magnetic flux level in an electromagnetic contactor. In one form a flux sensing device mounted in the contactor magnetic circuit provides a linear signal indicative of the level of magnetic flux in the contactor. A linear amplifier utilizes the flux signal to regulate contactor excitation to maintain flux at a desired value. In another form digital flux sensing device switches between first and second states as the level of magnetic flux varies between first and second values. A contactor excitation circuit "chops" the contactor excitation in response to the sensing device to thereby maintain magnetic flux at a value varying between the first and second values.