Industrial controller having redundancy and using connected messaging and connection identifiers to enable rapid switchover without requiring new connections to be opened or closed at switchover
AssigneeAllen-Bradley Company, Inc.
InventorsMark A. Flood, Mark E. Taylor
Life of this patent
Estimating the term…
Abstract
A redundant controller employs connection-based messaging to ensure reliability and determinacy in communications. The need to close connections and reopen connections with a backup module when control switches from a primary controller to a secondary controller is eliminated by keeping the secondary controller updated as to the connections that have been opened and having the secondary controller assume the connection identification numbers of the primary controller upon switch-over.
Claims12
A method of providing redundancy in an industrial controller having multiple control modules communicating data on a common link using connected messaging in which a connection identification number unique to a connection between control modules is used to schedule the data and allocate link resources to the transmission of the data, the control modules including a primary and secondary control module providing redundant function, the method comprising the steps of:
- (a) establishing a logical connection between a primary control module and another control module, the logical connection associated with a connection identification number;
- (b) transmitting the connection identification number from the primary control module to the secondary control module;
- (c) prior to a switch-over time, communicating data between the primary control module to the other control module using the connection identification number without transmission of data by the secondary control module using the connection identification number;
- and
- (d) after a switch-over time, communicating data between the secondary control module to the other control module using the connection identification number transmitted in step (b) without transmission by the primary control module using the connection identification number;
- whereby no new connections need to be opened and no connections need to be closed at the switch-over time.
A method of providing redundancy in an industrial controller system having multiple modules communicating data on a common link using connected messaging in which a connection identification number unique to a connection between control modules is used to schedule the data and allocate link resources to the transmission of the data, the modules including a primary and secondary control module providing redundant function, the method comprising the steps of:
- (a) establishing a logical connection between a primary control module and another control module, the logical connection associated with a connection identification number;
- (b) transmitting the connection identification number from the primary control module to the secondary control module, (c) prior to a switch-over time, communicating data between the primary control module to the other control module using the connection identification number without transmission of data by the secondary control module using the connection identification number;
- and
- (d) after a switch-over time, communicating data between the secondary control module to the other control module using the connection identification number transmitted in step (b) without transmission by the primary control module using the connection identification number;
- whereby no new connections need to be opened and no connections need to be closed at the switch-over time
- whereby the logical connection is established by the primary module sending to the other module an open connection message.
An industrial controller comprising:
- a common communications link;
- multiple control modules programmed generally to communicate on the common link with connected messaging in which a connection identification number unique to a logical connection between control modules is used to schedule data and allocate link resources to the transmission of the data;
- and programmed specifically to:
- (a) establish a logical connection between a primary control module and another control module, the logical connection associated with a connection identification number;
- (b) transmit the connection identification number from the primary control module to the secondary control module;
- (c) prior to a switch-over time, transmit data from the primary control module to the other control module using the connection identification number without transmission of data by the secondary control module;
- and
- (d) after a switch-over time, transmit data from the secondary control module to the other control module using the connection identification number transmitted without transmission by the primary control module;
- whereby no new connections need to be opened and no connections need to be closed.
Dependencies are inferred from the claim text.