Communication bus suitable for use in a hazardous area of a process plant
First Claim
1. A communication bus suitable for use in a hazardous area of a process plant to transmit electrical signals from one process device to a second and different process device disposed within the process plant and to interrupt the transmission of electrical signals in response to the detection of a fault condition in the communication bus, the communication bus comprising:
- a first end to connect to the one process device;
a second end to connect to the second and different process device;
a first transmission path between the first end and the second end that communicates electrical signals in a first direction between the first end and the second end;
a second transmission path between the first end and the second end that communicates electrical signals in a second direction between the first end and the second end; and
a safety device coupled to each of the first and second transmission paths between the first and second ends, wherein the safety device includes a first control unit to detect a fault condition associated with the communication bus, and wherein the safety device further includes a first switch unit connected to the first and second transmission paths and having a closed position allowing a flow of electrical signals along the first and second transmission paths and an open position preventing the flow of electrical signals along the first and second transmission paths, and wherein the first control unit causes the first switch unit to move to the open position to interrupt the flow of electrical signals between the first and second ends along each of the first and second transmission paths in response to detecting a fault condition in the communication bus at the first control unit, wherein the first control unit does not use the first and second transmission paths to detect the fault condition in the communication bus.
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Accused Products
Abstract
A communication bus suitable for use in a hazardous area of a process plant includes a first transmission path adapted to communicate electrical signals in a first direction, and a second transmission path adapted to communicate electrical signals in a second direction. A safety device is coupled to each of the first and second transmission paths and includes a control unit adapted to detect a fault condition associated with the communication bus. The safety device further includes a switch unit adapted to interrupt the flow of electrical signals along each of the first and second transmission paths in response to the detected fault condition. In this manner, the detection circuitry of the communication bus automatically reduces or prevents the occurrence of sparks or arcing in the event of a fault condition associated with the communication bus.
29 Citations
40 Claims
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1. A communication bus suitable for use in a hazardous area of a process plant to transmit electrical signals from one process device to a second and different process device disposed within the process plant and to interrupt the transmission of electrical signals in response to the detection of a fault condition in the communication bus, the communication bus comprising:
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a first end to connect to the one process device; a second end to connect to the second and different process device; a first transmission path between the first end and the second end that communicates electrical signals in a first direction between the first end and the second end; a second transmission path between the first end and the second end that communicates electrical signals in a second direction between the first end and the second end; and a safety device coupled to each of the first and second transmission paths between the first and second ends, wherein the safety device includes a first control unit to detect a fault condition associated with the communication bus, and wherein the safety device further includes a first switch unit connected to the first and second transmission paths and having a closed position allowing a flow of electrical signals along the first and second transmission paths and an open position preventing the flow of electrical signals along the first and second transmission paths, and wherein the first control unit causes the first switch unit to move to the open position to interrupt the flow of electrical signals between the first and second ends along each of the first and second transmission paths in response to detecting a fault condition in the communication bus at the first control unit, wherein the first control unit does not use the first and second transmission paths to detect the fault condition in the communication bus. - View Dependent Claims (2, 3, 4)
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5. A communication bus suitable for use in a hazardous area of a process plant to transmit electrical signals from one process device to a second and different process device disposed within the process plant and to interrupt the transmission of electrical signals in response to the detection of a fault condition in the communication bus, the communication bus comprising:
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a first end to connect to the one process device; a second end to connect to the second and different process device; a first transmission path between the first end and the second end that communicates electrical signals in a first direction between the first end and the second end; a second transmission path between the first end and the second end that communicates electrical signals in a second direction between the first end and the second end; a safety device coupled to each of the first and second transmission paths between the first and second ends, wherein the safety device includes a first control unit to detect a fault condition associated with the communication bus, and wherein the safety device further includes a first switch unit connected to the first and second transmission paths and having a closed position allowing a flow of electrical signals along the first and second transmission paths and an open position preventing the flow of electrical signals along the first and second transmission paths, and wherein the first control unit causes the first switch unit to move to the open position to interrupt the flow of electrical signals between the first and second ends along each of the first and second transmission paths in response to detecting a fault condition in the communication bus at the first control unit; and a third transmission path between the first and second ends and coupled to the safety device, wherein the first control unit is configured to detect the fault condition on the third transmission path and to cause the first switch unit to move to the open position to interrupt the flow of electrical signals between the first and second ends along each of the first and second transmission paths in response to detecting the fault condition on the third transmission path at the first control unit. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A safety device adapted for use in a hazardous area of a process plant, the safety device comprising:
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a communication bus including a first end to connect to one process device and a second end to connect to a second process device, first, second and third transmission paths disposed between and communicatively connecting the first end and the second end, wherein transmission paths are disposed between the one process device and the second process device disposed at different locations within the process plant and the first and second transmission paths are coupled to communicate electrical signals between the one process device and the second process device; a first control unit coupled to the third transmission path to detect a fault condition on the third transmission path associated with the communication bus; and a first switch unit coupled to the first and second transmission paths between the first end and the second end and to the first control unit and having a closed position allowing a flow of electrical signals along the first and second transmission paths and an open position preventing the flow of electrical signals along the first and second transmission paths, wherein the first control unit causes the first switch unit to move to the open position to interrupt the flow of electrical signals along the first and second transmission paths between the first end and the second end in response to detecting the fault condition associated with the communication bus on the third transmission path at the first control unit. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A method for providing a communication bus suitable for use in a hazardous area of a process plant, the method comprising:
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communicating electrical signals from a first process device to a second process device by communicating the electrical signals from a first end of the communication bus to a second end of the communication bus along a first transmission path and a second transmission path disposed between and communicatively connecting the first end and the second end of the communication bus; communicating electrical signals along a third transmission path within the communication bus; measuring an electrical characteristic associated with the third transmission path; detecting a fault condition associated with the communication bus in response to the measured electrical characteristic associated with the third transmission path; and interrupting the flow of electrical signals along the first and second transmission paths at a point between the first end and the second end of the communication bus in response to detecting a fault condition associated with the communication bus on the third transmission path. - View Dependent Claims (34, 35, 36, 37, 38, 39)
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40. A communication bus suitable for use in a hazardous area of a process plant to transmit electrical signals from one process device to a second and different process device disposed within the process plant and to interrupt the transmission of electrical signals in response to the detection of a fault condition in the communication bus, the communication bus comprising:
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a first end to connect to the one process device; a second end to connect to the second and different process device; a first transmission path between the first end and the second end that communicates electrical signals in a first direction between the first end and the second end; a second transmission path between the first end and the second end that communicates electrical signals in a second direction between the first end and the second end; a safety device coupled to each of the first and second transmission paths between the first and second ends, wherein the safety device includes a first control unit to detect a fault condition associated with the communication bus, and wherein the safety device further includes a first switch unit connected to the first and second transmission paths and having a closed position allowing a flow of electrical signals along the first and second transmission paths and an open position preventing the flow of electrical signals along the first and second transmission paths, and wherein the first control unit causes the first switch unit to move to the open position to interrupt the flow of electrical signals between the first and second ends along each of the first and second transmission paths in response to detecting a fault condition in the communication bus at the first control unit; and a third transmission path and a fourth transmission path connected in a loop within the communication bus, wherein the safety device is coupled to each of the third and fourth transmission paths and wherein the control unit includes a signal source to send a generated signal through the third transmission path and receives a received signal on the fourth transmission path and detects a fault condition based on the received signal.
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Specification