Programmable controller

An improved programmable controller of the type having processing means including a central processing unit (CPU), including associated means for solving user logic defining a control program comprising a plurality of nodes arranged in a network format comprising lines of nodes, each node representing a user selectable circuit element that can reference a selected coil power bit so as to determine the logical output of the node, the logical outputs of the lines of nodes in such networks each represented by a coil power bit, an addressable memory for the storage of data words corresponding to said user logic representing the user defined nodes, and an input/output (I/O) system for communicating input data from external devices to the processing means and for transferring output data representing the logical outputs of at least some of said lines of nodes from the processing means to the external devices for control thereof in response to the control program, and a bus interconnecting the CPU, addressable memory and I/O system, wherein the improvement comprises:

• (A) a first-in, first-out (FIFO) memory connected to the bus for receipt of user node data words from the addressable memory, the FIFO memory retrieving and outputting said data on a first-in, first-out basis, and further wherein the output of the FIFO memory contains said data words and is connected to the bus for simultaneous transfer to the CPU and the I/O system,
• (B) means included in the CPU logic solver means and interconnected to the bus for determining from the data word received from the FIFO memory the contact type of each node representing a relay element, and
• (C) means included in the I/O system and interconnected to the bus for receiving the same data word received by the CPU from the FIFO memory and for substantially simultaneously determining the state of the coil power bit referenced by the relay element in the data word,
• whereby a single data word represents different information to different portions of the programmable controller for its substantially simultaneous execution.