Abstract: A method and apparatus used with a motor controller having a PWM inverter for eliminating discontinuities in a stator current that are caused by noise, command signal discontinuities and feedback corrections. While noise, discontinuities, and correction can cause multiple crossings between a carrier signal and a command signal during a half cycle of a carrier signal, the present invention only allows a single crossing during any carrier signal half cycle to effect motor operation.

Abstract: A circuit interrupter provides a conducting path between two conductors and interrupts the conducting path in response to overcurrent conditions in the conductors. The interrupter includes a magnetic core around which the conductors are disposed. Each conductor is electrically coupled to an arc runner and a spanner is biased into contact with the arc runners to compete a conducting path between the conductors. A secondary response mechanism is provided adjacent to the core and includes arms extending around the core and a magnetic body. In response to overcurrent conditions of a first magnitude the body of the secondary response mechanism is attracted to the core causing the arms to displace the spanner out of contact with the arc runners. In response to overcurrent conditions of a second magnitude, such as due to direct short circuits, the spanner is repelled rapidly to a non-conducting position and the secondary response mechanism is attracted to the core to hold the spanner in the non-conducting position.

Abstract: The base plate module of an electromagnetic switching device, specifically a contactor, is mounted on a base plate (1). The base plate module contains the core (2) of the electromagnet, a magnet coil (5), a printed circuit board (10) with its connected ancillary devices, as well as the contact plugs (16, 17) and terminals (24, 25), both of which are accessible from the outside. Printed circuit board (10) is mounted on base plate (1) and is located between base plate (1) and core (2), which is mounted on the base plate. Strip conductors (12, 13, 14), on the side facing core (2), feature several spring-loaded stub contacts (19, 20) and/or contact plugs (21, 22), all of which are vertically mounted on circuit board (10). Flange (7) of coil module (6), which is oriented toward base plate (1), provided with terminals (23) of magnet coil (5). With magnet coil (5) in the mounted position, terminals (23) of magnet coil (5) are in contact with the spring-loaded stub contacts (19) of strip conductors (13).

Abstract: A hybrid active filter shunts three-phase power with passive elements tuned to have low impedance at a frequency of harmonic distortion. The passive elements are in series with controlled voltages sources providing cancelling currents to the harmonic currents. Rapid determination of the harmonic currents is provided in real-time through the use of a Park transformation reducing the variables which need to be manipulated. Measured currents as transformed are used to model undistorted current based on an average power consumed by the load. When the undistorted current is subtracted from the actual current, a harmonic current signal is produced that may be used to drive the voltage sources. The time domain method requires rapidly computed running averages and thus may be performed in-between the acquisition of the measured current samples.

Abstract: Backlighting for an LCD display is provided by a direct backlight unit which is hinged to the front panel in which the display is mounted. When closed, the backlight unit lamps and reflector transmit light directly against the back of the display. The reflector surfaces are made by a combination of constant radius, hyperbolic, parabolic and flat surfaces which maximize the emitted light transmitted to the display and help fill in for any failed or dimmed light sources.

Abstract: A method and apparatus to be used with a motor controller for determining if phase currents in a three phase AC motor are balanced. The phase angles between current zero crossing times for consecutive phase currents are compared to determine current balance and thyristor switches are employed to adjust phase angles and rebalance unbalanced currents.

Abstract: Subprograms together making up an industrial controller program are encapsulated in shells which make explicit the connection relationships and data flow directions of the subprogram normally implicit in the sharing of variables. The shells also identify the consumer/producer relationship of the variables as may be used to identify data contention problems. Actual connections between subprograms along which variables may be shared are externalized in a connection database that permits ready cross-referencing of such data sharing. Connection information stored in the shell may be used when a shell is cut and pasted to provide an initial suggestion of how to connect the new pasted shell. The automatic reconnection of the pasted shell refers to the previous connections and makes use of a hierarchical arrangement previously determined by the programmer reflecting the logic of the program.

Abstract: The present invention provides an efficient method of transferring multi-word data across a fixed width parallel bus normally transmitting a single word at a time by allocating part of the bus word to the transmission of a fractional address dividing the given addressing space into subaddresses or "fractional addresses". A data transfer request provides the desired fractional address and the data transfer response returns the fractional address value and the portion of the multi-word data corresponding to that fractional address.

Abstract: An industrial controller Input/Output module includes on-board processing circuitry in the form of a microprocessor and associated memory, a first programmable logic circuit and a second programmable logic circuit connected through an isolation interface. The isolation interface is comprised of optical coupling circuits. The programmable logic circuits are programmed to provide circuitry for parallel-to-serial data conversion of 24 bits of system Input/Output data on each side of the isolation interface. The data is then transferred as serial data in both directions at once in response to a shift clock signal. The data signals and the shift clock signal utilize three one-bit optical coupling devices in the isolation interface. After transfer across the isolation interface, the system Input/Output data is converted to parallel data for further processing.

Abstract: A digital communication network carries high and low priority data. The network stations that produce high priority data are assigned to a first group of stations and stations that produce low priority data are assigned to a second group with the two group not being mutually exclusive. Activity on the network is divided into periodic intervals of the same duration. Network control information, that defines how access to the medium, is determined is broadcast to all stations during a first segment of a periodic interval. The network control information defines the length of the periodic interval and of the periodic interval segments, and defines how many stations are in each group. Then during a second segment of the periodic interval, every station in the first group is afforded an opportunity, in a predefined order, to transmit high priority data over the medium.

Abstract: A method and apparatus to be used with a motor controller for determining the speed of the motor rotor using current zero crossing times of the stator winding currents. An error signal set, consisting of phase angle errors between consecutive zero crossings over a sampling period, is generated and analyzed in a region of interest in either the time or frequency domain, producing a signal frequency, the signal frequency being the frequency of the motor rotor.

Abstract: A method and apparatus used with a motor controller that detects load imbalance at a relatively low speed and, if the degree of load imbalance is greater than a predetermined acceptable maximum degree, produces an alarm signal that indicates an imbalanced load. If the degree of load imbalance is greater than the predetermined acceptable maximum value, the present invention may either attempt to rebalance the load or stops the motor until the balance can be manually adjusted.

Abstract: A modular product assembly platform which includes a multiple number of industrial robots or other similar assembly devices. The product assembly platform also includes a programmable controller system housed in a logic control cabinet, a vision control system housed in a vision control cabinet and a set of robot controllers which operate together to control the robots or assembly devices for performing product assembly tasks. The layout and configuration of the platform and the control equipment provide for convenience and flexibility in configuring and reconfiguring the assembly platform for different assembly procedures associated with different products.

Abstract: A bar code reader mirror oscillator is disclosed herein. The oscillator includes a permanent magnet having first and second poles of opposite polarity and an electromagnet having a core with first and second pole locations. The permanent magnet is fastened to a mirror carrier resiliently mounted to a frame to oscillate about a rotational axis, wherein the electromagnetic core is fastened to the frame so that the poles of the permanent magnet are equidistant from the pole locations of the electromagnet. This oscillator configuration directs substantially all of the energy applied to the electromagnet to the production of oscillatory motion in the associated reader mirror.

Abstract: Activity on a digital communication network is divided into periodic intervals and during a segment of each periodic interval a moderator station broadcasts a numerical count of the periodic intervals to all stations on the network. Each station has a memory in which a numerical value is stored, and a comparator that compares the numerical value to the numerical count received from the network. When the numerical count of the periodic intervals equals the numerical value, an apparatus within the station performs a defined operation, such as transmitting a message over the network or synchronizing a clock in the station to a master time standard. The equality of the periodic interval count and the numerical value also can be used to determine when to signal an external device. By using the count of the periodic intervals in this manner, the operation of several stations on the network can be coordinated.

Abstract: A bar code reader for reading bar codes falling within a rectangular scan area having two vertical sides, a top and a bottom is disclosed herein. The reader includes two oscillating mirrors operable to scan a light beam over the area. Each mirror is oscillated by an assembly controlled by a control circuit which produces controls signals which define the rate and frequency at which the mirrors are oscillated. More specifically, the mirror which sweeps the light beam between the vertical sides of the area is oscillated at a constant frequency, and the mirror which causes the mirror to progressively sweep between the top and bottom of the area is rotated so that a greater number of sweeps occur when the light beam progresses from the bottom to the top of the area than when the light beam progresses from the top to the bottom of the area.

Abstract: A bar code reader including a dynamic damper for an oscillating mirror assembly is disclosed herein. The reader includes a frame which supports a light source for producing scanning light, and a transducer for receiving scanning light reflected from a bar code being read by the reader. The light produced by the light source is scanned over the bar code by an oscillator assembly including a carrier defining a rotational axis, a light reflector fastened to the carrier, and a spring assembly fastened to the carrier and the frame to resiliently support the carrier for oscillation about the rotational axis. A damper fastened to the frame and slidably engaged with the carrier is provided to inhibit oscillation of the carrier perpendicular to the rotational axis. Such undesirable oscillation is typically caused by forces external to the scanner such as jarring of a structure supporting the scanner.

Abstract: A highly distributed industrial control system employs a number of separate control modules communicating together on a shared communications medium. Each module emulates one or more basic electrical parts having electrical terminals, such as switches and relays, and transmits production messages indicating the state of the parts, such as conducting current or not. A connection list for each part in each control module defines message identifiers of other parts whose production messages are received by the control module and interpreted as current flow to one or more of its parts. The control system is programmed by generating a schematic on a programming terminal showing connections of terminals on symbols of the parts such as would represent actual wiring of the emulated parts. A parts layout diagram is used in conjunction with the schematic to identify each part to a physical module.

Abstract: A harmonic analyzer using a short sampling window eliminates truncation artifacts in the sampling of an AC power waveform by equating the length of the sample period to a period of the sampled waveform. The period of the AC power waveform is estimated from the waveform and used to produce a set of "resampled" points evenly spaced within that period as estimated from the sampled. By performing a spectrum analysis on the resampled points, artifacts at the harmonic intervals are reduced to zero.

Abstract: A bus bar having reduced parasitic inductance and equal current path legends. A bus bar of the present invention has a first plate connected to a collector of a first transistor, a collector of a second transistor, an emitter of a third transistor and an emitter of a fourth transistor; a second plate including a second plate input connected to a collector of the third transistor and a collector of the fourth transistor; a third plate including a third plate input connected to an emitter of the first transistor and an emitter of the second transistor; and a fourth plate which is connected to the first plate. The first plate, the second plate, and the third plate are disposed such that the lengths of the current paths from the fourth plate through the first transistor to the input of the third plate is equal to the length of the current path from the fourth plate through the second transistor to the input of the third plate.