Abstract: A method for visually displaying the status of edits utilizes a plurality of visual indicia proximal the portions of edited program segments. Program segments which have not been edited and are currently part of the executable program in the programmable logic controller's processor are represented with solid power rails. Edited rungs which have either been inserted, replaced or deleted are noted as such by I, R and D indicia proximal the power rail of the rung. An asterisk symbol (*) is used to visually identify rungs that have been modified at the workstation but which have not yet been downloaded to the controller. Other visual indicia identify to a workstation operator rungs which have been verified. When the controller is put into test edits mode, the state of the program in the controller prior to downloading the edited program segments is maintained but is not executed and the edits are resolved into the program executing in the processor.

Abstract: A compiler for an industrial controller uses a user modifiable instruction table to contain code fragments necessary to compile particular instructions. During compilation, the instructions are replaced with the code fragments. Thus new instructions recognizable by the compiler may be added simply by editing this instruction table. Multiple instructions having the same name are resolved through a best match of operand types which examines the possible data loss in conversion of operand types to select a particular one of the instructions.

Abstract: A system for accurately determining a torque current i.sub.qe for use in field oriented control of an induction motor at low rotor frequencies (e.g., about half of the motor rated frequency) which provides an ideal no load current and still enables high torque at low speed. The system includes a frequency/correction angle identifier which, based on an applied stator voltage frequency, provides a correction angle which is added to a perceived phase angle to generate a corrected phase angle which is used to calculate the torque current component i.sub.qe. The torque current component is then used by a slip calculator and an IR compensator to adjust motor operation.

Abstract: A method of handling a fault which occurs during execution of an executable program comprises the steps of designating a first sequence of instructions of the executable program as visible and designating a second sequence of instructions of the executable program as invisible. According to this scheme, for the first visible sequence of instructions, faults are reported in a manner which designates an instruction at which the fault occurred. For the second invisible sequence of instructions, faults are reported in a manner which designates the invisible sequence of instructions as a whole. The invention permits fault handling for instructions added by a user to be performed in the same way as fault handling for built-in functions, and is usable with compiled machines.

Abstract: An industrial controller executing a graphical language employs a comparator circuit for monitoring the address locations of memory used to store the control program and its data. A cursor positioned on a graphics representation of the program is used to identify a particular graphical element to be monitored and the address of the starting instruction for that element is loaded into the comparator. An interrupt generated by the comparator causes the generation of a histogram listing the particular rungs name and the times at which it has been executed, useful for verifying and monitoring the operation of a control program. A snapshot of data values used by the element of the program at the time of its execution may also be stored to verify the condition under which the element executes.

Abstract: A method and apparatus for essentially eliminating turn-on delay distortions in terminal voltages and currents in a three phase motor control system wherein a compensator provides correction voltages which are added to command voltages as a function of feedback current amplitudes. Also a method for calibrating an open loop turn-on delay compensator during a commissioning procedure using a closed loop current controller.

Abstract: A processor-based control system including a host processor, a data receiver device, a system memory, and an intelligent DMA controller. The DMA controller includes a pre-parsing section. The pre-parsing section interrogating a received data packet to determine whether the received data packet contains an error, is valid, is a null packet or whether the host processor must be contacted.

Abstract: The apparatus and method of the present invention overcome the difficulties of balancing paired LVDT probes via provision of a quick and inexpensive process that can be implemented in either hardware or software. In particular, a software method is provided for determining a balance correction factor for paired probes in a LVDT gauging system. The balance correction factor is found through a procedure in which an operator moves a part under measurement within a fixture to which the probes are installed. The balance correction factor is then used to mathematically normalize A/D counts from individual paired probe circuits into a single result for each pair.

Abstract: A Manchester decoder blanks random transitions prior to the reception of a valid Manchester encoded signal. Specifically, the decoder according to the present invention comprises a data input, and edge detector, and a blanking device. The edge detector is used to detect edges in a signal which is received by the data input. Thus, in the event that edges are not detected at predetermined intervals (signifying that a valid signal is not being received), the blanking device blanks a data output of the decoder. Advantageously, the decoder circuit filters random transitions prior to the reception of a valid Manchester encoded signal, is of simple construction, and may be implemented in conjunction with a decoder circuit which is used to separate the Manchester encoded signal into its data and clock components.

Abstract: A program for partitioning a centrally developed industrial control program into component that may be download to distributed devices for execution and control of an industrial process divides elements of the control program into spatially linked elements which are associated with physical devices that have defined locations and spatially independent elements that have no defined location within the control structure. The spatially linked elements are grouped together according to their proximity and the spatially independent elements are assigned to those groupings so as to minimize communications between the various links. The cost of the grouping, the band width of the signals and the capabilities of the modules are also considered.

Abstract: A digital filter with a reduced filtering time. On/off data provided by eight contacts are read at predetermined time intervals, and the on/off data are stored in 8-bit binary data. (four-to one-cycle-previous data and new data). Logical AND and logical OR between the data are carried out to obtain AND result X and OR result Z, logical operations between the previous result In-1 and AND result X is carried out to obtain a result Y, and logical AND between the result Y and the OR result Z is carried out. A bit "A" whose AND result X is "1" is set again to "1", and a bit B whose OR result Z is "0" is set again to "0".

Abstract: A bidirectional lateral insulated gate bipolar transistor (IGBT) includes two gate electrodes. The IGBT can conduct current in two directions. The IGBT relies on a RESURF operation to provide high voltage blocking in both directions. The IGBT is symmetrical, having N-type drift region in contact with an oxide layer. A P-type region is provided above the N-type-drift region, having a portion more heavily doped with P-type dopants. The RESURF operation can be provided by a buried oxide layer or by a P substrate or by a horizontal PN junction. The IGBT can be utilized in various power operations, including a matrix switch or a voltage source converter.

Abstract: A method of editing a real-time control program as it controls equipment is provided in which the editing occurs in a second area of memory and integrated into the pre-existing program by means of conditional jump instructions concatenated to that edited material. The pre-existing program is uninterrupted by the editing process except for a change of single instructions which do not affect the results of the execution but redirect the execution thread of that control program to be conditionally connected to the edited material. This single writing of single instructions, which do not affect execution results, precludes the possibility of the controller executing partially edited programs. The jump instructions are conditional on a test edit pointer to allow instantaneous implementation of the edits and a simple return to unedited instructions simply by changing the state of the flag.

Abstract: The arrangement for the control of an electromagnet is intended for an electromagnet consisting of a Stationary core 7, a pickup coil 1 through which current flows temporarily after the switch is closed, a holding coil 2 through which current flows during the operating state, as well as a moveable armature 8 moving in relation to the core 7. Within a magnetically responsive switching circuit 5, which is connected in series with the pickup coil 1, a coupling sensor 22 is included, consisting of at least one winding which is linked to at least a part of the magnetic field of the electromagnet at least then when the air gap is open. At the instant when the air gap is closed, the voltage spike induced in the sensor coil 22 switches a controllable semiconductor 11, connected in series with the pickup coil 1 into a state of high resistivity via an electronic switching circuit arrangement.

Abstract: A bus bar having reduced parasitic inductance and equal current path lengths. 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 and arranged 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.

Abstract: The present invention constitutes a data crossloading system for use with a programmable controller system having primary and secondary (or "back-up") systems each of which have redundant hardware components and have data structures associated with these components. The present invention further relates to the interconnection of the hardware components and to the processes for providing redundant data structures which enable a secondary or back-up system to rapidly and effectively assume control when a malfunction occurs in a primary control system. Both systems are connected via the same remote data links to common I/O racks which interface to sensing and output devices on the equipment being controlled.

Abstract: A fixture is provided for facilitating the fabrication of a motor controller of the type including a power substrate module and a control circuit board mounted to and electrically coupled to the power substrate module via a plurality of conductors. The fixture is preferably a ring-like structure made of epoxy-fiberglass laminate. Apertures for engaging and holding the conductors are provided in the fixture at locations corresponding to conducting pads on the power substrate module. For fabrication, the power substrate module and the fixture are preformed and solder is disposed on the conducting pads of the module. During fabrication, the conductors are inserted into the apertures in the fixture and the fixture and conductors are positioned over the preformed power substrate module to bring the conductors into contact with the conducting pads. The fixture and power substrate module are then passed through a reflow oven to melt the solder and complete the connection of the conductors to the module.

Abstract: In an industrial controller associated with independent I/O modules for exchanging signals between a controlled machine and the controller, a control program executed by the controller is associated with an I/O map identifying functionality of the independent I/O modules. At initialization of the controller, function keys are transmitted to the I/O modules, the latter which confirm that they are capable of the functions expected by the control program. The I/O modules may change their function according to the function keys and may accept functions not identical to those performed by the I/O module if the I/O module performs at greater functionality.

Abstract: A variable frequency motor drive incorporating a circuit interrupter includes a rectifying circuit for converting incoming AC power to DC power and an inverting circuit for converting the DC power to controlled AC power in response to control signals. A control circuit implements a preset control routine to control operation of the inverting circuit to drive a motor in accordance with desired operating parameters. A circuit interrupter is coupled between the source of AC power and the rectifying circuit and includes an actuator for interrupting power to the drive in response to interrupt command signals from the motor control circuit. The motor drive includes a switching circuit and a capacitive circuit for powering the circuit interrupter. The drive control circuitry monitors operation of the drive and the motor and when conditions require removal of power to the drive, the control circuitry commands the switching circuit to close, energizing the circuit interrupter and thereby removing power to the drive.

Abstract: A bus structure for interconnecting the modules of an industrial automation controller includes DATA lines and associated control lines that enable interface circuits on each module to transfer frames of data. Modules connected to the bus structure support data transfers of differing widths and differing speeds, and interface circuits within each module automatically adapt to data width and speed differences between communicating modules. During a first bus cycle of each transfer, sending and receiving modules negotiate a bus width and clock speed to be used for the transfer by asserting their respective width and speed codes onto a set of wired-or status lines. After the first bus cycle, the status lines are then used for communicating alternate functions between the participating modules.