Redundant fieldbus system

• US 7,505,819 B2
• Filed: 02/08/2006
• Issued: 03/17/2009
• Est. Priority Date: 02/08/2006
• Status: Active Grant

• Current Assignee: Moore Industries International, Inc.
• Original Assignee: Moore Industries International, Inc.
• Inventors: El-Sayed, Hassan M.
• Primary Examiner(s): DeCady; Albert
• Assistant Examiner(s): DUNN, DARRIN D
• Application Number:
  US11/351,144
• Publication Number:
  US 20070185588A1
• Time in Patent Office: 1,133 Days
• Field of Search: 700/1, 700/21, 370227-228, 714/4
• US Class Current: 700/21
• CPC Class Codes: G05B 9/03 with multiple-channel loop, i.e. redundant control systems

Abstract

A redundant fieldbus redundant system includes two independent conditioned power modules which automatically detect cable faults, such as short or open circuits on both the host and field sides of the network. The power modules are interfaced directly on one side to the primary and backup H1 cards of the host system, and are directly interfaced on the other side to an automatically terminating network device coupler module which provides connections to field devices. The redundant fieldbus system provides power and communications in a parallel physical configuration between the host system and the field devices irrespective of any single point failure in the network. In case of a fault, the redundant fieldbus system automatically eliminates the faulty section of the network, switches power and communications to the healthy portion of the network and terminates the network for signal integrity.

Claims

1. A fieldbus network, comprising:

a first power supply module comprising a first power supply and host and field power supply paths coupling the first power supply to a host side terminal and to a field side terminal of the first power supply module, respectively, the first power supply module having a first fault detector circuit coupled to a host switch coupled along the host power supply path between the first power supply and the host side terminal and to a field switch coupled along the field power supply path between the first power supply and the field side terminal, the host switch adapted to decouple the first power supply from the host terminal in response to detection of a fault on the host side and the field switch adapted to decouple the first power supply from the field side terminal in response to detection of a fault on the field side;

a second power supply module comprising a second power supply and host and field power supply paths coupling the second power supply to a host side terminal and to a field side terminal of the second power supply module, respectively, the second power supply module having a second fault detector circuit coupled to a host switch coupled along the host power supply path between the second power supply and the host side terminal and to a field switch coupled along the field power supply path between the second power supply and the field side terminal, the host switch adapted to decouple the second power supply from the host terminal in response to detection of a fault on the host side and the field switch adapted to decouple the second power supply from the field side terminal in response to detection of a fault on the field side; and

first and second fieldbus cables coupled in parallel to a field device, the first fieldbus cable coupled between the field side terminal of the first power supply and the field device and the second fieldbus cable coupled between the field side terminal of the second power supply and the field device.

2. The fieldbus network of claim 1, further comprising a device coupler providing a first current path between a first set of terminals and the field device and a second current path between a second set of terminals and the field device, the first set of terminals connected to the first fieldbus cable and the second set of terminals connected to the second fieldbus cable, the first power supply provides power to the field device only over the first fieldbus cable and the first current path and the second power supply provides power to the field device only over the second fieldbus cable and the second current path, wherein during fault free operation both the first power supply and the second power supply power the field device.

3. The fieldbus network of claim 2, wherein the first fault detector includes a short circuit detector and an open circuit detector and wherein while the first fault detector detects a fault, the fieldbus network powers the field device only over the second fieldbus cable.

4. The fieldbus network of claim 1, wherein the first fault detector includes a first open circuit detector coupled to the host side, a second open circuit detector coupled to the field side, and a short circuit detector coupled to both the host side and the field side.

5. The fieldbus network of claim 1, wherein the second fault detector includes a short circuit detector and an open circuit detector wherein when the second fault detector detects a fault, the fieldbus network powers the field device over the first fieldbus cable.

6. The fieldbus network of claim 1, wherein the second fault detector includes a first open circuit detector coupled to the host side, a second open circuit detector coupled to the field side, and a short circuit detector coupled to both the host side and the field side.

7. The fieldbus network of claim 1, wherein the host side terminal of the first power supply module is coupled to a first noise filter and wherein the field side terminal of the first power supply is coupled to the first noise filter and wherein the first noise filter passes bidirectional communication signals between the host side terminal and the field side terminal of the first power supply module at least when no fault is present on the host side and the field side of the first power supply module.

8. The fieldbus network of claim 7, wherein the host side terminal of the second power supply module is coupled to a second noise filter and wherein the field side terminal of the second power supply is coupled to the second noise filter and wherein the second noise filter passes bidirectional communication signals between the host side terminal and the field side terminal of the second power supply module while the first fault detector detects a fault.

9. The fieldbus network of claim 1, further comprising an automatic termination circuit that terminates a connection between the first and second fieldbus cables in response to a fault on one of the first and second fieldbus cables, the termination circuit coupled between the first fieldbus cable and the field device and between the second fieldbus cable and the field device.

10. The fieldbus network of claim 2, the device coupler further comprising an automatic termination circuit that terminates a connection between the first and second fieldbus cables in response to a fault on one of the first and second fieldbus cables, the automatic termination circuit coupled between the first fieldbus cable and the field device and between the second fieldbus cable and the field device.

11. The fieldbus network of claim 1, further comprising a static termination circuit coupled to both of the first and second power supply modules.

12. The fieldbus network of claim 2, further comprising a first static termination circuit coupled to both of the first and second power supplies and a second static termination circuit within the device coupler.