Abstract: A network interface board provides a communication link between a personal computer and a network bus connecting a plurality of programmable logic controllers. The network interface board mounts in an expansion slot of the personal computer. The programmable logic controllers control the operation of various machines. The network interface board includes mailbox registers for storing messages from the network, including three different queues of alarm messages which the personal computer can access in any order. These messages could be in the form of program steps, allowing the personal computer to directly program a programmable logic controller over the communication network.

Abstract: A control system contains a communications network, a host computer and a programmable logic controller (PLC). The host computer includes prioritized alarm queues for receiving prioritized alarms from the programmable logic controller. Alarms fall into either a local or a global category, and each category supports three types of alarms: warnings, alerts or faults.

Abstract: A control system allows for transferring messages between a programmable logic controller and a host computer over an Ethernet communications network. The messages include a routing address specifying an originating drop number, a destination drop number, and a routing drop number. The system is responsive to the routing address for transferring the messages between the programmable logic controller and the host computer. The host computer can immediately obtain messages from a programmable logic controller without interruption of the execution of its ladder program. The host computer can also receive unsolicited messages from the programmable logic controller.

Abstract: A control system allows for transferring messages between a programmable logic controller and a host computer over a serial data communications network. The programmable logic controller executes a ladder program and has an integral network interface module for permitting direct communicative coupling to the communications network. Messages can be received and sent by the programmable logic controller without interruption of the execution of the ladder program. The programmable logic controller can receive unsolicited messages from the host computer.

Abstract: A transfer network interface module provides a communication link between a data communications network bus connecting a plurality of processor based devices and a redundant processing system. The redundant processor system has first and second processor based devices communicatively coupled to at least one other remote based device by means of the data communication network. The first processor based device operates on an active status and the second processor based device operates on a backup status until a switch occurs. The switch causes the second processor based device to begin operation on active status. The transfer network interface device is communicatively disposed between the first and second processor based devices and the data communications network and permits continuous communication between either of the first and second processor based devices and the remote processor based device regardless of which of the first and second processor based devices is on active status.

Abstract: "A Manufacturing Automation Protocol (MAP) interface unit couples a local area network (LAN) to a MAP network. The LAN includes a plurality of industrial programmable logic controllers (PLCs) and the MAP network includes a plurality of MAP devices. The MAP interface unit comprises a CPU for performing a plurality of routines. A first routine controls the coupling of the MAP interface unit to the MAP network and a second routine controls the coupling of the MAP interface unit to the LAN. A further routine disposed between the first coupling routine and the second coupling routine converts messages from the MAP devices on the MAP network to messages to the PLCs on the LAN and converts messages from the PLCs to messages to the MAP devices. These messages are either requests for data or responses with data to these requests.

Abstract: A drum-type sequencer operable in a ladder logic program and capable of being selectively stepped in various modes; that is, in forward stepped sequence, non-sequentially, and backwardly.

Abstract: An expanded register rack assembly is for a processor based device. The expanded register rack assembly has a first board register rack assembly having multiple slots for receiving multiple electronic modules including a programmable controller module. The expanded register rack also has a second register rack having multiple slots for receiving multiple electronic modules. The expanded register rack assembly further has a communicative coupling between the first and second board racks, the communicative coupling permitting the programmable controller module to selectively access any of the other electronic modules received in the first and second multiple slots without the need for communication hardware mounted in any of the slots.

Abstract: Add-in program instructs operable through a general purpose spreadsheet program in a personal computer to move real-time status and control messages directly between cells in the displayed spreadsheet and addressed registers of programmable logic controllers (PLCs) is disclosed. The PLCs operate such as machine tools for processing stations and connect together and to an interface card in the personal computer over a network. The invention facilities a user's real-time monitoring and control of the manufacturing performed at the machine tools or processing stations through mathematical and logical features of the spreadsheet, which are well known and easy for a user to implement.

Abstract: A high-speed press control system including a control processor and an associated scan processor for executing a press algorithm providing timed interrupts and consisting of identical programmable sub-algorithms to control output and input registers. The high-speed press control system has the capability of monitoring and reacting to press position every 2.5 ms.

Abstract: A communication network for programmable logic controllers (PLC) wherein selected memory means of each PLC has at least two ports directly accessible by other PLC and certain registers of the PLC are identical. Each PLC further has an interblock gap timer to signal the PLC when its transmit time slice is to occur. The time slice consists of a block transmit time and an interblock gap time. The total update time has been optimized to engable efficient, high-speed transfer of blocks of data between the PLCs.

Abstract: A housing for a multi-board electronic module is disclosed. The housing comprises a rear wall, side walls, a top wall and a bottom wall cooperating to define an enclosure having an open front. Brackets located in the enclosure permit mounting of the electronic circuit boards in a substantially vertical orientation. Vent openings in the top and the bottom walls cooperate with the vertically oriented electronic circuit boards to permit air heated by the electronic components located on the circuit boards to escape the housing through the top wall vent openings and for permitting ambient air to enter the bottom wall vent openings. The ambient air replaces the escaping air and cools the components located on the electronic circuit boards. The housing can be either wall mounted or mounted in a register rack assembly.

Abstract: A register rack assembly for housing a plurality of electronic modules including a programmable controller and related devices, each of the modules containing an electronic circuit board, is disclosed.

Abstract: A circuit board housing 10 includes a front wall 26 which has openings therein for exposing input/output devices on the circuit board 12. A bracket 70 has L-shaped tab 92 and L-extension 82 for maintaining alignment between the input/output devices 64 and the windows 60. The housing also has a removable cover 50 and a removable door 80 that are easily removable for ready access to internal components.

Abstract: A multiple processor communications system including a control processor and a scan processor having its own program counter enabling the efficient execution of subroutines. The scan processor directly accesses a compiled user memory which contains its operating program and also directly accesses the image memory which contains the input and output data to perform the computations required by the program. The system includes error codes for distinguishing various error conditions including collision error conditions indicating illegal commands to the scan processor when it is scanning and parity errors in the compiled user memory and in the image memory.

Abstract: A communication network for programmable logic controllers (PLCs) wherein selected memory means of each PLC have at least two ports directly accessible by other PLCs and certain registers of the PLCs are identical to enable efficient, high-speed transfer of blocks of data between the PLCs.