Patent ID: 7032029
Filing Date: 2006-04-18
Classification: G05B

Abstract:
1. A method of providing an active standby control system comprising the step of: providing a first and a second programmable logic controller, each programmable logic controller having an operating state, an I/O scanner having a connection to a remote I/O head, and a hot standby nodule, wherein each programmable logic controller's hot standby module is operably connected together, operably connecting each programmable logic controller to a network; assigning a network address identifier to each programmable logic controller, wherein the network address identifier is a Media Access Control address; placing the first programmable logic controller in primary mode and the second programmable logic controller in secondary mode; sensing the operating state of each programmable logic controller; exchanging the network address identifiers between the first programmable logic controller and the second programmable logic controller upon detection of a failure in the first programmable logic controller; and resetting the connection between the I/O scanner and the remote I/O head in the first primary programmable logic controller prior to exchanging the network address identifiers.