Programmable controller with I/O expansion module located in one of I/O module positions for communication with outside I/O modules

US4882702A · kind A · utility

Assignee

• Allen-Bradley Company, LLC · US

Inventors

• Odo J. Struger · Chagrin Falls, US
• Mark Luboski · Euclid, US
• Timothy J. Murphy · Hudson, US

Key dates

• Filing date: May 16, 1988
• Grant date: Nov 21, 1989
• Expiry date: May 16, 2008

Classification

• Technology area (CPC G): Physics
• CPC primary: G05B2219/15119
• WIPO field: Control
• WIPO sector: Instruments

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. Besides the backplane controller, the I/O expansion module includes a serial channel controller, a common memory and arbitration circuity which allows the controllers to alternate access to the common memory and to exchange data. The serial channel controller controls multiplexing and demultiplexing of I/O status data with the I/O modules through the serial data channel.