Method and apparatus for an active standby control system on a network

A method of providing an active standby control system comprising the steps of:

• providing a first programmable logic controller and a second programmable logic controller, each controller having an operating state the first programmable logic controller being in an active state, the second programmable logic controller being in a standby state;
• providing an IO module;
• and,
• operably connecting the first programmable logic controller, the second programmable logic controller and the IO module through a network connector and a fiber optic network cable, the operably connected first programmable logic controller, the second programmable logic controller, the IO module, the fiber optic cable and the connector forming a sub-network;
• wherein data is transferred throughout the sub-network at a rate of at least 100 Mb/s;
• and
• providing a switch for controlling signal communication over the fiber optic network cable to avoid signal collisions and maintain determinism on the sub-network.

A method of providing an active standby control system comprising the steps of:

• a first programmable logic controller and a second programmable logic controller, the first programmable logic controller being in an active state, the second programmable logic controller being in a standby state each controller having an operating state;
• providing an IO module;
• operably connecting the first programmable logic controller, the second programmable logic controller, the IO module and a network connector with a fiber optic network cable and forming a sub-network, wherein the network connector is a switch for controlling signal communication over the fiber optic network cable to avoid signal collisions and maintain determinism throughout the sub-network, and wherein data is transferred throughout the sub-network at a rate of at least 100 Mb/s;
• controlling signal communication over the sub-network;
• assigning a network identifier to each controller;
• placing one the first programmable logic controller in primary mode and the other the second programmable logic controller in secondary mode;
• sensing the operating state of each the first programmable logic controller, wherein the network identifier of each the first programmable logic controller is selected in response to the operating state of each respective the first programmable logic controller;
• exchanging the network identifiers between the first programmable logic controller and the second programmable logic controllers;
• and,
• transmitting a reverse address resolution protocol (RARP) message.