Allen-Bradley Company, LLC

Alan C Cribbs

Kendal R Harris

Timothy J Murphy

Robert C Weppler

Margarita M Hutz

Jack D Calderon

David A Karpuszka

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.

Backplane data transfer technique for industrial automation controllers

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 send and receive frames of data. An arbitration circuit in each module employs arbitration lines in the bus structure to conduct a two phase competition to determine which module receives the next bus mastership. The arbitration lines include a set of wired-or weight code lines and a single arbitration strobe line. Modules desiring control of the bus structure assert a local weight code onto the weight code lines and determine which module is asserting the numerically greatest local weight code. Arbitration is conducted separately on the bus structure and a winning module is ready to transfer its data frame as soon as the previous winner completes its transfer and relinquishes control of the bus structure. The winning weight code identifies both the source address of the winning module and the priority of the data frame to be sent, and is latched by all modules on the backplane bus as an arbitration vector to provide advance identification of the next module to transmit and the priority of the message.

Method for and apparatus for operating a local communications module in

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North Canton, OH, United States of America

Alan C Cribbs