Patent ID: 8631174

Claim:
A linking device for facilitating communications of one or more command signals between an external controller and at least one Fieldbus device, the linking device comprising: at least one communications interface configured to communicate special-purpose signals to the external controller, the special-purpose signals being a first timing message and a second timing message; and at least one processing component configured to: direct the communication of the first timing message and the second timing message by the communications interface, wherein the first timing message is output by a primary linking device for receipt by the external controller and the second timing message is output by a secondary linking device for receipt by the external controller, wherein the primary linking device and the secondary linking device are configured to communicate with each other; initiate a first timer and a second timer to monitor a first time period and a second time period, in which respective responses to the first timing message and the second timing message are received; determine whether a response to the first timing message has been received from the external controller by the primary linking device within a first predetermined time period based upon an evaluation of the first timer; based on the determination that no response to the first timing message has been received from the external controller within the first time period, query, by the primary linking device, the secondary linking device, in order to determine whether the secondary linking device has received a response to the second timing message within the second time period based upon an evaluation of the second initiated timer; receiving, at the primary linking device, a confirmation from the secondary linking device that the response to the second timing message has been received from the external controller by the secondary linking device within the second time period; and direct, based upon the confirmation, switching of communications control of the one or more command signals to the secondary linking device that facilitates communications between the external controller and the at least one Fieldbus device.