CAN bus automatic line termination

• US 8,597,054 B2
• Filed: 03/07/2011
• Issued: 12/03/2013
• Est. Priority Date: 03/07/2011
• Status: Active Grant

• Current Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Original Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Inventors: Dozier, Ross E., Beam, Jeffrey Stephen, Topp, Eric
• Primary Examiner(s): NASRI, JAVAID H
• Application Number:
  US13/042,041
• Publication Number:
  US 20120231663A1
• Time in Patent Office: 1,002 Days
• Field of Search: 439/620.04, 439/188, 439/676
• US Class Current: 439/620.04
• CPC Class Codes: G06F 13/4086 Bus impedance matching, e.g. termination
• CPC Class Codes: H04L 25/0298 Arrangement for terminating transmission lines

Abstract

A network interface includes a receptacle configured to receive a plug, a first contact and a second contact each disposed in the receptacle, and a combination of a resistive element and a normally closed switch arranged in series with each other. The combination is coupled between the first contact and the second contact, and has a first configuration in which the switch is opened responsive to a presence of the plug within the receptacle, and a second configuration in which the switch is closed responsive to an absence of the plug from the receptacle.

Claims

1. A network interface, comprising:

a receptacle configured to receive a plug;

a first contact and a second contact each disposed in the receptacle; and

a combination of a resistive element and a normally closed switch arranged in series with each other, the combination coupled between the first contact and the second contact, the combination having a first configuration in which the switch is opened responsive to a presence of the plug within the receptacle, and a second configuration in which the switch is closed responsive to an absence of the plug from the receptacle, and wherein the combination and the receptacle are configured such that insertion of the plug into the receptacle pushes the switch from closed to open.

2. The network interface of claim 1, wherein the switch includes the first contact, wherein the first contact is movable from a first position to a second position responsive to the presence of the plug within the receptacle, wherein the switch is closed when the first contact is in the first position, and wherein the switch is open when the first contact is in the second position.

3. The network interface of claim 2, wherein the first contact is movable from the second position to the first position responsive to the absence of the plug from the receptacle.

4. The network interface of claim 3, wherein the switch includes the second contact, wherein the second contact is movable from a third position to a fourth position responsive to the presence of the plug within the receptacle, and wherein the second contact is movable from the fourth position to the third position responsive to the absence of the plug from the receptacle.

5. The network interface of claim 1, wherein the switch includes a microswitch.

6. The network interface of claim 1, further comprising a lever coupled to the switch and configured to open the switch responsive to an insertion of the plug into the receptacle.

7. The network interface of claim 6, wherein the lever is further configured to close the switch responsive to a removal of the plug from the receptacle.

8. The network interface of claim 1, wherein the receptacle includes an RJ45 jack.

9. The network interface of claim 1, wherein the resistive element includes a 120-ohm resistor.

10. The network interface of claim 1, wherein the network interface is included in a device configured to communicate on a Controller Area Network (CAN).

11. A network interface, comprising:

a receptacle configured to receive a plug;

a first contact and a second contact each disposed in the receptacle;

a resistive element selectively coupled between the first contact and the second contact for providing resistive termination between the first contact and the second contact; and

means for detecting the presence and absence of the plug in the receptacle, coupling the resistive element between the first contact and the second contact responsive to detecting the absence of the plug, and decoupling the resistive element from at least one of the first contact and the second contact responsive to detecting the presence of the plug by pushing the first and the second contact apart.

12. The network interface of claim 11, further comprising a switch coupled in series to the resistive element for switchably coupling the resistive element between the first contact and the second contact.

13. The network interface of claim 12, wherein the switch includes the first contact, wherein the first contact is movable from a first position to a second position responsive to the presence of the plug within the receptacle, wherein the switch is closed when the first contact is in the first position, and wherein the switch is open when the first contact is in the second position.

14. The network interface of claim 11, wherein the receptacle includes an RJ45 jack.

15. The network interface of claim 11, wherein the resistive element includes a 120-ohm resistor.

16. A method of terminating a communication bus within a network interface, the method comprising:

inserting a plug within a receptacle of the network interface;

disabling resistive termination between a first contact of the receptacle and a second contact of the receptacle responsive to insertion of the plug by pushing the first and second contact apart within the receptacle;

removing the plug from the receptacle; and

enabling resistive termination between the first contact and the second contact upon removal of the plug from within the receptacle.

17. The method of claim 16, wherein disabling resistive termination includes moving the first contact from a first position to a second position responsive to inserting the plug within the receptacle, wherein the first contact in the first position is switchably coupled to a resistive element, and wherein the first contact in the second position is switchably decoupled from the resistive element.

18. The method of claim 17, wherein enabling resistive termination includes moving the first contact from the second position to the first position responsive to removing the plug from the receptacle.

19. The method of claim 16, wherein disabling resistive termination includes mechanically opening a switch coupled in series to a resistive element in response to an insertion of the plug into the receptacle.

20. The method of claim 19, wherein enabling resistive termination includes mechanically closing the switch in response to a removal of the plug from the receptacle.