System and method of powering and communicating field ethernet device for an instrumentation and control using a single pair of powered ethernet wire

• US 6,640,308 B1
• Filed: 11/22/1999
• Issued: 10/28/2003
• Est. Priority Date: 04/16/1999
• Status: Expired due to Term

• Current Assignee: Schneider Electric Systems USA, Inc. (Schneider Electric SE)
• Original Assignee: Invensys Systems Incorporated (Invensys PLC)
• Inventors: Baker, William, Thibault, Richard, Keyghobad, Seyamak
• Primary Examiner(s): Butler, Dennis M.
• Assistant Examiner(s): Patel, Nitin C.
• Application Number:
  US09/444,827
• Time in Patent Office: 1,436 Days
• Field of Search: 370/254, 370/257, 390/395.52, 390/395.5, 713/300
• US Class Current: 713/300
• CPC Class Codes: G05B 19/042 using digital processors G05B19/05 takes precedence
• CPC Class Codes: G05B 19/4185 characterised by the network communication
• CPC Class Codes: G05B 2219/25132 Superposition data signals on power lines for actuators
• CPC Class Codes: G05B 2219/25428 Field device
• CPC Class Codes: G05B 2219/31121 Fielddevice, field controller, interface connected to fieldbus
• CPC Class Codes: G05B 2219/31135 Fieldbus
• CPC Class Codes: G05B 2219/31145 Ethernet
• CPC Class Codes: G05B 2219/33208 Superposition of control signals on supply lines
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A powered Ethernet connection is provided between two devices connected by an Ethernet connection that provides data communication between the devices. Electrical power is applied to the Ethernet connection at the first device, and extracted from the Ethernet connection at the second device. The extracted power is used to power the second device.

Claims

1. A method of connecting a four-terminal Ethernet connection to a two-wire Ethernet connection, the method comprising:

providing a device having a four-terminal Ethernet connection, the connection including a first pair of terminals for transmitting data away from the device and a second pair of terminals for transmitting data to the device;

providing a two-wire Ethernet connection for transmitting data to and from the device;

providing a switched connection between the four-terminal Ethernet connection and the two-wire Ethernet connection, the switched connection operating in a first mode in which the two-wire Ethernet connection is connected to the first pair of terminals and a second mode in which the two-wire Ethernet connection is connected to the second pair of terminals;

setting the switched connection to operate in the first mode;

monitoring the two-wire Ethernet connection for data being transmitted to the device;

setting the switched connection to operate in the second mode upon detection of data being transmitted to the device; and

injecting power onto the two-wire Ethernet connection at the device for use in powering another device connected to the two-wire Ethernet connection.

2. The method of claim 1, further comprising changing an impedance presented to the two-wire Ethernet connection at the device from a first impedance when the switched connection is operating in the first mode to a second impedance when the switched connection is operating in the second mode.

3. An industrial process field device for use with a powered Ethernet connection, the industrial process field device comprising:

communications circuitry operable to exchange data with an industrial process control device over an Ethernet connection using an Ethernet protocol;

power circuitry operable to extract operating power from the Ethernet connection; and

process circuitry operable to;

sense a physical condition of an industrial application and to transmit information about the sensed physical condition to the industrial process control device using the Ethernet connection;

or

control the physical condition of the industrial application in response to a process command received from the industrial process control device through the Ethernet connection.

4. The industrial process field device of claim 3 wherein the communications circuitry and the power circuitry are operable to interface with the Ethernet connection and the Ethernet connection comprises only a single pair of wires.

5. A method of providing data and electrical power to an industrial process field device, the method comprising:

injecting an electrical power signal onto an Ethernet connection;

transmitting the electrical power signal and control data over the Ethernet connection, the control data being generated by a control device;

extracting the electrical power signal and the control data at the industrial process field device for an industrial application, the instrumentation device implementing an instrumentation operation using the electrical power signal;

collecting physical data at the instrumentation device; and

receiving the physical data at the control device via the Ethernet connection.

6. The method of claim 5 further comprising:

generating modified control data at the control device, based on the physical data;

transmitting the modified control data to the instrumentation device, over the Ethernet connection; and

modifying the instrumentation operation, to thereby modify the industrial application.

7. The method of claim 5 wherein the Ethernet connection is a four-wire connection.

8. The method of claim 5 wherein injecting the electrical power signal occurs at the control device.

9. The method of claim 5 wherein injecting the electrical power signal occurs at a hub device associated with the control device.

10. The method of claim 5 wherein the Ethernet connection comprises two pairs of wires, with a first pair of wires being used to transmit data from the control device to the industrial process field device and a second pair of wires being used to transmit data from the industrial process field device to the control device.

11. The method of claim 10 wherein injecting the electrical power signal comprises applying a DC voltage across the two pairs of wires by coupling a first potential to the first pair of wires and a second potential to the second pair of wires, with the DC voltage being defined as a difference between the two potentials.

12. The method of claim 11 wherein:

each pair of wires is connected to a corresponding transformer at the first device,

each transformer includes a center-tapped primary winding, and

coupling potentials to the pairs of wires comprises applying the DC voltage between the center taps of the primary windings of the two transformers.

13. The method of claim 11 wherein:

a center-tapped inductor is connected across each pair of wires at the first device, and

coupling potentials to the pairs of wires comprises applying the DC voltage between the center taps of the inductors.

14. The method of claim 11 wherein:

each pair of wires is connected to a corresponding transformer at the second device,

each transformer includes a center-tapped winding, and

extracting the electrical power signal comprises extracting a DC voltage existing between the center taps of the windings of the two transformers.

15. The method of claim 11 wherein:

a center-tapped inductor is connected across each pair of wires at the second device, and

extracting electrical the electrical power signal comprises extracting a DC voltage existing between the center taps of the inductors.

16. The method of claim 5 wherein the Ethernet connection comprises a single pair of wires used to transmit data from the control device to the industrial process field device, to transmit data from the industrial process field device to the control device, and to provide power form the first device to the second device.

17. The method of claim 16 wherein injecting the electrical power signal comprises applying a DC voltage across the pair of wires by coupling a first potential to the first wire through an inductor and coupling a second potential to the second wire through an inductor, with the DC voltage being defined as a difference between the two potentials.

18. The method of claim 5 wherein the industrial process field device is a monitor operable to sense a process condition and to transmit information about the sensed process condition to the first device using the Ethernet connection.

19. The method of claim 5 wherein the industrial process field device is an actuator operable to control a process condition in response to a command sent from the control device over the Ethernet connection.

20. A method of providing data and electrical power to an industrial process field device, the method comprising:

injecting an electrical power signal onto a two-wire Ethernet connections;

transmitting the electrical power signal and control data over the two-wire Ethernet connection, the control data being generated by a control device;

extracting the electrical power signal and the control data at the industrial process field device for an industrial application, the instrumentation device implementing an instrumentation operation using the electrical power signal;

collecting physical data at the instrumentation device; and

receiving the physical data at the control device via the two-wire Ethernet connection.

21. The method of claim 20 further comprising:

providing a first connection for transmitting the control data;

providing a second connection for receiving the physical data;

providing a switch connected to the two-wire Ethernet connection, and operable to switch between the first connection and the second connection;

contacting the switch to the first connection when transmitting the control data; and

contacting the switch to the second connection when receiving the physical data.

22. The method of claim 21 further comprising:

detecting the physical data at the first connection; and

switching the switch from the first connection to the second connection.

23. An industrial control system comprising:

an industrial controller operable to output control data;

an Ethernet connection including at least a first pair of wires, the first pair of wires being operable to communicate both the control data and an electrical power signal; and

a monitor connected to the Ethernet connection and operable to receive the electrical power signal and the control data to thereby monitor an industrial application.

24. The system of claim 23 further comprising an actuator operable to modify the industrial application based on the control data.

25. The industrial control system of claim 23 wherein the Ethernet connection is a four-wire connection.

26. The industrial control system of claim 23 wherein the Ethernet connection is a two-wire connection.

27. The industrial control system of claim 26 further comprising:

a first connection operable to output the control data;

a second connection operable to input physical data from the monitor; and

a switch operable to switch between the first connection when transmitting the control data and the second connection when transmitting the physical data.

28. The system of claim 27 further comprising a detector operable to detect the physical data at the first connection and signal the switch to switch to the second connection.

29. The system of claim 27 wherein the first and the second connections are located at the control device.

30. The system of claim 27 wherein the first and the second connection are located at a hub port connected to the control device.

31. An industrial control system comprising:

an industrial controller operable to output control data;

an Ethernet connection including at least a first pair of wires, the first pair of wires being operable to communicate both the control data and an electrical power signal; and

an actuator connected to the Ethernet connection and operable to receive the electrical power signal and the control data to thereby actuate a process in an industrial application.

32. A method of transmitting data comprising:

outputting transmit data over a first connection;

inputting receive data over a second connection;

providing a two-wire Ethernet connection operable to transfer the transmit data and the receive data;

providing an electrical power signal over the two-wire Ethernet connection; and

switching a switch connected to the two-wire Ethernet connection between the first connection for transferring the transmit data over the two-wire Ethernet connection and the second connection for transferring the receive data over the two-wire Ethernet connection.

33. The method of claim 32 further comprising:

detecting receive data at the first connection; and

signaling the switch to switch between the first connection and the second connection.

34. A data transfer system comprising:

a transmitter operable to output transmit data;

a first connection associated with the transmitter and operable to output the transmit data;

a second connection associated with the transmitter and operable to input receive data;

a two-wire Ethernet connection operable to transfer the transmit data and the receive data;

a switch connected to the two-wire Ethernet connection and operable to switch between the first connection when transmitting the transmit data and the second connection when transmitting the receive data; and

a power injector operable to provide an electrical power signal over the two-wire Ethernet connection.

35. The data transfer system of claim 34 comprising:

a detector operable to detect the receive data at the first connection, further operable to signal the switch to switch between the first connection and the second connection in response thereto.

36. The data transfer system of claim 35 wherein the transmitter is associated with a control device, and further wherein the power injector is co-located with the control device.

37. The data transfer system of claim 35 wherein the transmitter is associated with a network hub device, and further wherein the power injector is co-located with the network hub device.