Network interface board having memory mapped mailbox registers including alarm registers for storing prioritized alarm messages from programmable logic controllers

US5251302A · kind A · utility

Assignee

• Square D Company · US

Inventors

• Edward H. Weigl · Deerfield, US
• David J. Sackmann · Milwaukee, US
• Steven Gans · San Jose, US

Key dates

• Filing date: Dec 26, 1991
• Grant date: Oct 5, 1993
• Expiry date: Dec 26, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G05B2219/15101
• WIPO field: Control
• WIPO sector: Instruments

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.