Abstract: A method of partitioning a control program among many spatially separated computing devices places most of the program instructions in computing devices supporting outputs to the controlled processor equipment. Inputs then simply report their data to the output computing devices rather than having that data processed by a path of computing devices communicating with each other such as may cause the evaluation of the outputs to be delayed by multiple transmissions on the common link.

Abstract: A method for a distributed processing system which includes the steps of developing a control program for controlling outputs at a plurality of I/O nodes, distributing executable portions of the program to the I/O nodes through a network, broadcasting input status data from the I/O nodes on the network and controlling the outputs at the I/O nodes in response to the input status data broadcast on the network and the executable portions of the program residing at the I/O nodes.

Abstract: Fuzzy logic programming is provided for machine and process controllers. New input and output instructions are devised for ladder diagram programming, as well as methods of downloading fuzzy logic instructions from a programming terminal to a programmable controller processor and methods for executing such instructions in the programmable controller processor.

Abstract: An industrial controller monitors its state as comprised of selected inputs and outputs for a present time period and a previous time period. Each current state is compared to a previously acquired list of stored states to detect possible errors in inputs to the industrial controller and to find the closest match of the current state to a previously stored state. This "closest match word" is used to identify erroneous inputs to the industrial controller and to determine whether the controlled process must be halted. The closest match word may be substituted for the current state to permit the controlled process to continue.

Abstract: A cluster of control processors are interconnected by a local area network and exchange data to carry out their control functions. Each controller executes a control program containing both conventional instructions and T-instructions which call for an operation on data maintained by another controller in the cluster. All data required to execute T-instructions is stored in a virtual I/O image table and each controller is responsible for keeping its section of this table up-to-date by periodically broadcasting its data on the local area network.

Abstract: The capacity of programmable controllers with a processor module and I/O modules connected in a single equipment rack is expanded by connecting an I/O expansion module in one of the positions normally occupied by a conventional I/O module. The I/O expansion module communicates with the processor module through the rack backplane and also communicates with other racks of I/O modules and with node I/O modules through a serial data channel. Data for I/O modules on the serial data channel are stored in a bulk storage area in the processor module to expand the effective size of an image table of I/O status data that is maintained by the processor module. The processor module is programmed to operate with a backplane controller in the I/O expansion module to transfer data in or out of the bulk storage area.

Abstract: In a programmable controller, addresses for a group of input/output modules are decoded to generate an enable signal to each respective module. To increase the density of I/O circuits per module without increasing the width of the data bus, the I/O modules are provided with enabling circuits that are responsive to a pair of associated enabling signals in one method of I/O scanning and responsive to an enabling signal and two or more byte addresses received in another method of I/O scanning. Circuit paths have been added on a backplane circuit board to allow each enable signal to be coupled to a pair of I/O modules in the first method of I/O scanning. In the second method of I/O scanning, the hardware for carrying out the first method is disabled and byte addresses are used to couple multiple bytes of I/O status to each I/O module.

Abstract: A programmable controller has input and output multiplexer modules through which I/O data may be transferred. A multiplexer array is stored in the controller memory for storing this I/O data and conventional programmable controller instructions in the user control program may be employed to examine or set specified bits in the stored array. The multiplexer module may take the form of two separate modules in which one module generates a select code to a matrix of switches or operating devices and the other module transfers data to or from a selected row in the matrix.

Abstract: An interchangeable keyboard application module is connected to a video monitor module in a computer terminal to provide sequences of processor instructions and a keyboard for performing a plurality of selectable applications. The video monitor module includes a CRT display, a serial I/O interface and a processor that processes characters received through the serial I/O interface for display on the CRT screen whether or not the application module is attached. The processor in the video monitor module detects the connection of the application module, and then selects its instructions from a memory in the application module first, to prompt the selection of a mode of operation for the terminal, and second to execute the selected mode of operation. The application module uses a plurality of keyboard overlays, each corresponding to a respective mode of operation. In a specific embodiment two of the modes of operation are programming applications related to programmable controllers.

Abstract: The control program for a programmable controller is entered and edited through a program terminal which displays the control program symbolically as a ladder diagram. Comment instructions are entered into the control program and associated comment data is entered and stored. The comment data is subsequently displayed by the program terminal along with the ladder diagram rung containing the comment instruction.

Abstract: Programmable controllers are connected in a ring by serial data links. Each controller periodically transmits information packets on the ring which contain its I/O image table data. All controllers on the ring receive such data and store it in their data tables, and such data is thus available for examination by each controller processor during its execution of the user's control program.

Abstract: A preferred embodiment of an input module is connected through six address terminals and four data terminals to six banks of contacts. A single bank address is coupled to two latches in the module and then to two banks of contacts. A nibble of data is coupled from each of two banks of contacts to each of two corresponding data latches on the module. The sequential addressing of a low nibble bank and a high nibble bank and the latching of data therefrom is controlled by sequencing circuitry which is enabled each time a bank address is written to the module. In a second embodiment coded information is output through the six address terminals and decoded by two external decoders to multiplex 256 inputs to the processor. Such modules are particularly useful in multiplexing a large number of inputs to the processor of a programmable controller.

Abstract: A secondary, protective triac is connected in series with a main load-control triac in an a-c output circuit for a programmable controller. The two triacs are coupled to a pair of digital inputs and when the main triac is conducting the secondary triac is not conducting--unless the main triac stays "on" after an "off" signal is received, signifying a shorted main triac. If that occurs, a triac-failure fuse is blown and the secondary triac switches to conduct current and complete a virtually short circuit through a main power fuse. The blowing of the triac-failure fuse illuminates a neon bulb to give an indication of a main triac failure, and the blowing of the main power fuse illuminates a corresponding neon bulb to indicate a failure on the module and its disconnection from the load.

Abstract: A programmable controller includes a microprocessor which operates in response to machine instructions stored in a read-only memory. A control program comprised of programmable controller-type instructions is stored in a random access memory. These are executed by translating their operation codes into the starting addresses of corresponding sets of machine instructions. In addition, one or more "universal instructions" may be contained in the control program, and when these are read from the random-access memory, they are translated to enable the microprocessor to execute a user defined set of microprocessor machine instructions. These user defined machine instructions may be stored in a read-only memory or they may be stored in the random access memory with the control program. The programmable controller may thus effectively be programmed in two languages, a programmable controller language and a microprocessor machine language.

Abstract: A programmable controller has a high density I/O module for interfacing eight analog input devices to a main processor module. The high density I/O module has a microcomputer for reading, storing and updating eight words of input data. The microcomputer also communicates with the main processor of the main processor module to transfer the eight words of input status data to a main memory. The main processor is programmed to communicate with the microcomputer in two alternate modes. In one mode the main processor is directed by an applications control program to individually couple words of the status data; in the other mode the main processor is directed by firmware instructions to alter the input/output scan and couple a block of input data.

Abstract: A programmable controller interfaces a numerical control system to sensing and operating devices that control the auxiliary functions on a machine tool. In the controller a microprocessor is coupled to a random-access memory (RAM) and an electrically alterable read-only memory (EAROM) through an address bus and a data bus. The RAM stores a user control program and an I/O image table that depicts the status of the sensing and operating devices on the machine tool. Under program control the microprocessor verifies the contents of the RAM and copies the verified contents into the EAROM. If the contents of the RAM are altered or lost, the master copy of data stored in the EAROM is reloaded into the RAM.

Abstract: A small, low-cost programmable controller is programmed with both bit-oriented and word oriented program instructions that are stored in a main memory. A microprocessor couples each program instruction to a respective interpreter routine of machine instructions stored in an interpreter memory. Bit-oriented program instructions with a common operation code but different bit-pointer codes are coupled to their own respective interpreter routines. The program instructions have operation codes and bit pointer codes that are assigned by a program panel, and are then translated by a translator PROM as they are coupled to an interpreter routine. Operand addresses are read through the translator PROM unchanged. Error-locating circuitry assists in detecting faulty chips in the main memory as the control program is executed. The hardware required to execute the control program is minimized, while the translator PROM allows the processor unit to be used with prior program panels.

Abstract: An input circuit for a digital control system includes a rectifier circuit, a current limiting circuit and a set of zener diodes which can be selectively employed to receive a wide variety of signals from industrial sensing devices. The signal is generated to an output drive circuit by an optocoupler which provides electrical isolation. The output drive circuit generates a logic level signal which is compatible with the digital electronic control system. The input circuit is particularly well suited for fabrication as an integrated circuit.

Abstract: A programmable controller includes a processor formed around a pair of four-bit bipolar microprocessors. A control program formed by selected macroinstructions is stored in a random access memory and it is executed by sequentially mapping each macroinstruction operation code into a corresponding microroutine which is stored in a read-only memory. Some macroinstructions include operand addresses of a line in an I/O image and data table portion of the random access memory, and one macroinstruction (ADX) expands this operand address to enable the I/O image and data table to be expanded in size. A timer macroinstruction is executed in part by reading the state of a counter which is driven by a real time clock, and arithmetic functions are performed with the use of a decimal adjust accumulator.

Abstract: A programmable controller with a processor module, one or more I/O modules and a rack in which the modules are supported, is expanded by replacing the processor module in a lead slot with a rack adapter module that connectes to a separate processor unit. The rack unit is converted from a controller rack to one of several I/O interface racks that can be connected to the separate processor unit. The removable processor module integrates the processing functions of the separate processor unit and the parity checking, decoding and buffering functions of the rack adapter module. The rack enclosure provides a universal connecter between the I/O modules and the module selected for insertion into the lead slot.