Common-mode noise reduction circuit
First Claim
1. A system operating in a process control environment, the system comprising:
- a field device to perform a process control function in the process control environment;
a remote device disposed away from the field device to perform an auxiliary function associated with the process control function of the field device;
a first wired communication link communicatively coupled to the field device and to the remote device to support data communication between the field device and the remote device; and
a common-mode noise reduction circuit coupled to the field device and to the wired communication link to reduce common-mode noise generated in the first wired communication link;
wherein the first wired communication link includes a plurality of electrical wires, and wherein each of the plurality of electrical wires connects to the field device at a respective one of a plurality of inputs;
wherein a first one of the plurality of electrical wires is associated with a first impedance at a first one of the plurality of inputs and a second one of the plurality of electrical wires is associated with a second impedance at a second one of the plurality of inputs, wherein the first impedance is substantially different from the second impedance; and
wherein the common-mode noise reduction circuit matches the first impedance to the second impedance so that the common-mode noise generates an equal voltage on the first one of the plurality of electrical wires and the second one of the plurality of electrical wires.
1 Assignment
0 Petitions
Accused Products
Abstract
A system operating in a process control environment includes a field device to perform a process control function in the process control environment, a remote device disposed away from the field device to perform an auxiliary function associated with the process control function of the field device, a first wired communication link communicatively coupled to the field device and to the remote device to support data communication between the field device and the remote device, and a common-mode noise reduction circuit coupled to the field device and to the wired communication link to reduce common-mode noise generated in the first wired communication link.
6 Citations
22 Claims
-
1. A system operating in a process control environment, the system comprising:
-
a field device to perform a process control function in the process control environment; a remote device disposed away from the field device to perform an auxiliary function associated with the process control function of the field device; a first wired communication link communicatively coupled to the field device and to the remote device to support data communication between the field device and the remote device; and a common-mode noise reduction circuit coupled to the field device and to the wired communication link to reduce common-mode noise generated in the first wired communication link; wherein the first wired communication link includes a plurality of electrical wires, and wherein each of the plurality of electrical wires connects to the field device at a respective one of a plurality of inputs; wherein a first one of the plurality of electrical wires is associated with a first impedance at a first one of the plurality of inputs and a second one of the plurality of electrical wires is associated with a second impedance at a second one of the plurality of inputs, wherein the first impedance is substantially different from the second impedance; and wherein the common-mode noise reduction circuit matches the first impedance to the second impedance so that the common-mode noise generates an equal voltage on the first one of the plurality of electrical wires and the second one of the plurality of electrical wires. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A method of operating a field device in a process control network, wherein the field device communicates with a remote device via a first wired communication link and with a process control network via a second wired communication link, and wherein the first wired communication link has a plurality of wires connected to the field device via a plurality of respective inputs, the method comprising:
-
obtaining a first input impedance to a signal on a first one of the plurality of wires at a first one of the plurality of inputs; obtaining a second input impedance to a signal on a second one of the plurality of wires at a second one of the plurality of inputs; and adjusting the second input impedance to match the first input impedance in order to reduce common-mode noise on the first communication link. - View Dependent Claims (9, 10)
-
-
11. A field device for use in a network operating in a process control environment, comprising:
-
an operational unit to perform a physical step in the process control environment; a first interface coupled to a first communication link to communicate with a remote device; a second interface coupled to a second communication link to communicate process control information to the network; and a common-mode noise reduction circuit coupled to the first interface to reduce common-mode noise generated in the first communication link; wherein the field device is associated with a floating ground; wherein the first communication link includes a plurality of electrical wires coupled to a plurality of respective inputs of the first interface; and wherein the common-mode noise reduction circuit includes an input impedance matching unit to match input impedance on each of the plurality of electrical wires at the respective one of the plurality inputs relative to the floating ground. - View Dependent Claims (14, 15, 16)
-
-
12. A field device for use in a network operating in a process control environment, comprising:
-
an operational unit to perform a physical step in the process control environment; a first interface coupled to a first communication link to communicate with a remote device; a second interface coupled to a second communication link to communicate process control information to the network; and a common-mode noise reduction circuit coupled to the first interface to reduce common-mode noise generated in the first communication link; wherein the first communication link includes a plurality of electrical wires coupled to a plurality of respective inputs of the first interface; and
wherein the common-mode noise reduction circuit includes an operational amplifier to maintain input AC impedance associated with at least two of the plurality of electrical wires at a substantially equal level. - View Dependent Claims (13)
-
-
17. A noise-reduction circuit for use with a device coupled to a wired communication link, wherein the device includes a plurality of inputs to connect to a plurality of wires of the wired communication link, the noise-reduction circuit comprising:
-
a first circuit input coupled to a first one of the plurality of wires at a first one of the plurality of inputs; a second circuit input coupled to a second one of the plurality of wires at a second one of the plurality of inputs; an impedance matching unit arranged to obtain an input AC impedance associated with the second one of the plurality of inputs, to obtain an input AC impedance associated with the first one of the plurality of inputs, and to adjust a first one of the AC impedances to match a second one of the AC impedances to provide matching input AC impedances at the first one of the plurality of inputs and at the second one of the plurality of inputs. - View Dependent Claims (18, 19, 20, 21, 22)
-
Specification