| US 7,519,737 B2 | ||
| Input/output (I/O) scanner for a control system with peer determination | ||
| Ron Naismith, N. Andover, Mass. (US); Allan Tanzman, Newton Centre, Mass. (US); Dean Papadopoulos, Groton, Mass. (US); Andy Swales, Windham, N.H. (US); and Orlando P. Metcalf, North Andover, Mass. (US) | ||
| Assigned to Schneider Automation Inc., North Andover, Mass. (US) | ||
| Filed on Mar. 02, 2002, as Appl. No. 10/87,888. | ||
| Prior Publication US 2003/0033030 A1, Feb. 13, 2003 | ||
| Int. Cl. G06F 15/16 (2006.01) | ||
| U.S. Cl. 709—245 [700/5; 700/7; 700/129; 710/8; 710/15] | 16 Claims |
| 1. A method comprising the steps of:
providing a first device on a first node of a communications network, the first device configured to connect to and scan I/O
devices;
providing a second device on a second node of the communications network, the second device configured to connect to and scan
the I/O devices;
assigning a first address to a the first node and a second address to a the second node, wherein the first address is characteristic
of a primary mode of operation;
initiating from the first node a first communications command in a peer protocol format addressed to the second node;
initiating from the second node a second communications command in the peer protocol format addressed to the first node;
identifying the second device on the second node as a peer device within the first device on the first node responsive to
receiving the second communications command at the first node;
identifying the first device on the first node as a peer device within the second device on the second node responsive to
receiving the first communications command at the second node;
wherein the peer device is a programmable logic controller (PLC) device;
scanning the I/O devices by the first device on the first node;
determining that the first node is inoperable;
initiating at the second node an exchange of the first address and the second address responsive to determining that the first
node is inoperable;
resetting a connection between the first device and the I/O devices responsive to determining that the first node is inoperable;
and
assigning the first address to the second node and the second address to the first node responsive to initiating the exchange.
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