Method for communicating among a plurality of programmable logic controllers
CA 2027334 C · Owner: Lacy, Andrew Moore · Inventors: Sexton, Daniel White; Lacy, Andrew Moore
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method is provided for communicating among a plurality of programmable logic controllers (PLC's) coupled together on a common bus. A master PLC and a plurality of slave PLC's are coupled to the bus. An attach signal is transmitted by the master PLC to address and select the particular slave PLC to which the master PLC desires to transmit a message. The master PLC then transmits a mailbox signal including data and message length information regarding a next message if not all data from the master PLC and intended for the slave PLC could fit in the mailbox message. Additional next messages, each including data and next message length information are sent by, the master PLC to the selected …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed October 11, 1990 and granted June 20, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended October 11, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 11, 2012.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
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Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.