Abstract: A microprocessor based program loader is connected to the memory data bus and memory address bus of a programmable controller. The program loader is responsive to commands entered through a keyboard to load and edit the programmable controller control program. A mode switch associated with the programmable controller provides a number of selectable positions which determine the mode of operation of the programmable controller and the functions that can be performed by the program loader. One of the positions on this mode switch enables the program loader through a control line to assume control of the mode selection. The operator can thus control the mode of operation through the program loader keyboard which may be located remotely from the programmable controller.

Abstract: A programmable controller sequentially executes a control program at a basic "scan rate" determined by the length of the program and the speed at which the controller processor executes the instructions therein. At the completion of each scan through the control program an I/O scan is performed which inputs the status of all sensing devices to the controller image table and outputs status data from the image table to operating devices. The present invention enables the status of selected sensing devices to be inputted and acted upon at any point during the scan through the control program and it enables the output of the processor logic unit to be coupled to a selected operating device at any point. The rate at which selected I/O devices can be scanned by the controller is thus programmable and may be much higher than the basic scan rate of the controller.

Abstract: A programmable controller for sensing the status of sensing devices and controlling the state of operating devices in accordance with a stored program includes a position encoder input module which receives position data. In response to instructions in the stored program, the position data from the input module is compared with an upper and a lower limit stored in the controller memory, and if the data lies outside the limits, the controller logic unit is forced to a false decision.

Abstract: A pair of spaced side plates are connected together by mounting bars which support a circuit board. Individual I/O modules plug into connectors on the circuit board and are fastened to the mounting bars. Wiring from the controller processor is brought into an adapter module which also plugs into the circuit board and external wiring is brought into terminal blocks which mount along the top and bottom edges of the circuit board. The wire terminals on the terminal blocks are connected to the conductive paths on the circuit board to provide electrical connection with the circuits in the I/O modules.

Abstract: A set of circuit boards are mounted side by side and electrical connection is made to terminal pads disposed along one edge of each circuit board by connectors which are carried by swing arms. The swing arms are rotatably mounted on a support rod which also mounts a set of lower guide rails supporting the set of circuit boards. A set of status indicator lights are disposed along the same edge of each circuit board above each swing arm. A swing arm latching mechanism holds the swing arm in a vertical operating position. A circuit board latching mechanism holds the circuit board in place when the swing arm is pivoted to a maintenance position.

Abstract: A data handling module connects to the memory of a programmable controller and operates to periodically steal memory cycles from the controller processor to read data out of the memory and write data into it. The data handling module includes a microprocessor which is programmed to perform a number of functions. The function to be performed is indicated by a control status register which is set by the control program and which is periodically examined by the data handling module. The status of the data handling module is also indicated by a register which is examined by programmable controller instructions. In response to directions indicated by the control status register, data files may be transferred between a data file storage and an active data file storage area and messages may be coupled to a TTY which connects to the data handling module.

Abstract: A program protection module for a programmable controller checks the critical, or protected, portion of the control program each time the controller is switched to the run mode. This is accomplished by reading each control program instruction out of the controller memory and comparing it with a corresponding control instruction stored in a nonaccessible read-only memory. If all the compared control instructions are identical, the module sets a status bit in the programmable controller which enables the protected portion of the control program to be executed. If identity is not found, an alarm is generated and the protected program is not executed.

Abstract: Fault detection hardware is employed at the I/O interface racks of a programmable controller to detect fault conditions which may occur there. An I/O fault line is connected in daisy chain fashion between the I/O interface racks and the controller processor, and when a fault is indicated at any of the I/O interface racks, it is communicated to the controller processor through this line. The indicated I/O fault freezes, or holds, a microprocessor in the controller processor, and if the I/O fault persists for a preselected time interval, all operating devices connected to the programmable controller interface racks are decontrolled. A watchdog timer is also provided in the controller processor for detecting malfunction conditions which may occur at the processor. When such a condition is detected, the operating devices connected to the programmable controller interface racks are decontrolled.

Abstract: A programmable controller includes a controller processor which operates in response to a control program to transfer command words stored in a data table to an input/output image table in the controller memory. An input/output scanner circuit operates asynchronously with respect to the controller processor to couple command words in the output image table to one or more of a plurality of word-oriented I/O modules and to couple command words from an I/O module to the input image table. A pulse module is described for receiving such command words and controlling the operation of a stepping motor and an analog output module is described which converts a digital number in such command words to an analog output signal.

Abstract: A programmable controller includes a hardwired monitor module which connects to the I/O address decoder and the central logic unit of the controller. The monitor module detects malfunctions which cause deviations in the operation of these elements from a prescribed pattern, and in response generates a disabling signal which deenergizes all operating devices on the controlled system. A diagnostic module is also included and is comprised of a set of routines stored in the controller memory which periodically direct the controller to operate according to a prescribed pattern and to indicate deviations from that pattern as a malfunction. Such malfunctions are indicated in a diagnostic register which connects to the monitor module.

Abstract: A controller programmer connects to a programmable controller and serves as a means for loading and editing the control program. When the contact histogram mode of operation is employed the logic state of a selected I/O device connected to the controller is monitored, and each time its status changes, its present status is recorded along with the time interval between status changes. A first embodiment is described in which the invention is employed in a hardwired controller program loader and a second embodiment is described in which the controller program loader employs a programmed microprocessor. In the first embodiment the status changes are recorded on paper tape and in the second embodiment they are recorded on a cathode ray tube screen.

Abstract: A programmable controller includes four remotely located input/output interface racks which are connected by cables to an I/O scanner circuit which is centrally located with the controller processor and memory. Input and output data is serially transmitted between the I/O scanner circuit and the interface racks, and fault processors are located in both the I/O scanner circuit and the interface racks to monitor the operation. The fault processors include fault tolerant detector circuits which ignore erroneous transmissions caused by industrial noise, but which initiate a shutdown process when malfunctions occur. The shutdown process is controlled by a programmable disabling circuit which is responsive to program instructions stored in the controller memory to allow independent, quasi-independent, or dependent operation of the machines connected to each of the four interface racks.

Abstract: A programmable sequence controller includes a plurality of I/O modules and a corresponding number of memory modules which are sequentially and continuously addressed by a scanning counter. A step counter selects a set of 16 instructions in each memory module which are sequentially read out by the scanning counter. A logic unit advances the step counter when conditions are met to advance to the next programmed step.