System for address initialization of generic nodes in a distributed command and control system and method therefor

• US 6,166,653 A
• Filed: 08/13/1998
• Issued: 12/26/2000
• Est. Priority Date: 08/13/1998
• Status: Expired due to Term

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Pigott, John M., Kruecken, Joachim, Schulmeyer, Peter Hans
• Primary Examiner(s): Zimmerman, Brian
• Assistant Examiner(s): Dalencourt, Yves
• Application Number:
  US09/133,226
• Time in Patent Office: 866 Days
• Field of Search: 340/825.52, 340/825.06, 340/825.08, 340/825.05, 370/438, 370/453, 370/471, 370/475, 370/252, 370/254, 370/258, 370/440, 370/457, 710/114, 710/9, 709/220, 709/223, 709/226, 709/245
• US Class Current: 340/9.16
• CPC Class Codes: G05B 19/042 using digital processors G05B19/05 takes precedence
• CPC Class Codes: G05B 2219/21028 Address of module determined by position
• CPC Class Codes: G05B 2219/25232 DCS, distributed control system, decentralised control unit
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 2012/40273 the transportation system being a vehicle
• CPC Class Codes: H04L 61/5038 for local use, e.g. in LAN or USB networks, or in a controller area network [CAN]

Abstract

A method and apparatus for assigning unique addresses to each generic "node" in a distributed control system that contains a main controller (52) coupled to a plurality of generic nodes (54) via a distributed communication bus (55). The main controller (52) provides currents and/or voltages to the communication bus (55) via a supply (58). In one embodiment, each node (54) processes the current and voltages to store reference voltages and distance voltages proportional to its distance along the communication bus (55). In another embodiment, each node (54) signals to the main controller (52) when the distance voltage reaches a certain value relative to the reference voltage. The main controller (52) processes the arrival times of these signals to determine a relative distance to each node (54). This distance information is used to assign a unique address to each generic node (54) for identification during normal mode of operation.

Claims

1. A method for initializing a distributed control system, the distributed control system having a control unit and at least one node coupled to a common communication bus, the distributed control system having a predetermined topology, the method comprising the steps of:

determining a distance from the control unit to each node, the distance representing a relative location of said node in the predetermined topology wherein determining the distance further comprises;

providing a reference current on the communication bus t develop a distance voltage on the communication bus at said node as a function of the distance of said node along the communication bus;

determining said distance as a function of said distance voltage; and

assigning a specific address to said node based on the relative location of said node in the predetermined topology.

2. The method of claim 1, wherein said determining said distance as a function of said distance voltage, comprises the step of:

measuring said distance voltage, said distance voltage representing the relative location of said node in the predetermined topology.

3. The method of claim 2, wherein the step of measuring, comprises the step of:

performing an analog-to-digital conversion of the distance voltage to provide a digital value.

4. The method of claim 1, further comprising the steps of:

providing a reference voltage on the common communication bus;

measuring the reference voltage at said node; and

correcting the distance voltage using said measured reference voltage.

5. The method of claim 4, wherein, within the predetermined topology, the relative location of each node on the common communication bus, relative to the control unit, is selected such that the distance from said control unit to said node differs from the distance from the control unit to each other node.

6. The method of claim 5, wherein the distance from said control unit to said node differs from the distance from the control unit to each other node by at least a predetermined minimum distance.

7. The method of claim 4, further comprising the step of:

correlating the distance of said node to a predetermined node function; and

wherein the step of assigning a specific address to said node is further characterized as assigning a specific address to said node based upon the correlated node function.

8. The method of claim 4, wherein the step of determining the distance from the control unit to each node, further comprises the steps of:

sending a data value on the communication bus from said node to the control unit, the data value identifying the relative location of said node;

determining validity of said data value; and

resending the data value if the data value is not valid.

9. The method of claim 8, wherein the step of determining validity is performed by the control unit.

10. The method of claim 8, wherein the step of determining validity is performed by said node.

11. The method of claim 1, wherein the distance from said control unit to said node differs from the distance from the control unit to each other node by at least a predetermined minimum distance.

12. The method of claim 1, wherein, within the predetermined topology, the relative location of each node on the common communication bus, relative to the control unit, is selected such that the distance from said control unit to said node differs from the distance from the control unit to each other node.

13. The method of claim 12, wherein the distance from said control unit to said node differs from the distance from the control unit to each other node by at least a predetermined minimum distance.

14. The method of claim 1, further comprising the step of:

correlating the distance of said node to a predetermined node function; and

wherein the step of assigning a specific address to said node is further characterized as assigning a specific address to said node based upon the correlated node function.

15. The method of claim 1, wherein the step of determining the distance from the control unit to each node, further comprises the steps of:

sending a data value on the communication bus from said node to the control unit, wherein the data value is related to the location of said node;

determining validity of said data value; and

resending the data value if the data value is not valid.

16. The method of claim 15, wherein the step of determining validity is performed by the control unit.

17. The method of claim 15, wherein the step of determining validity is performed by said node.

18. The method of claim 14, wherein the step of resending is further characterized as resending, after a random time interval, said data value.

19. The method of claim 1, wherein the step assigning a specific address further comprises the step of:

correlating the distance of said node to a predetermined node function; and

wherein the specific address is related to said node function.

20. The method of claim 19, wherein the step of assigning is performed by the control unit.

21. The method of claim 20, further comprising the step of communicating said address to said node via said common communication bus.

54. The method of claim 1, wherein the at least one node is a generic node.

22. A method for initializing a distributed control system, the distributed control system having a control unit and at least one node coupled to a common bus, the distributed control system having a predetermined topology, the method comprising the steps of:

determining a distance from the control unit to each node, the distance representing a relative location of said node in the predetermined topology, by;

providing a reference current on the communication bus to develop a distance voltage on the communication bus at said node as a function of the distance of said node along the bus; and

determining said distance as a function of said distance voltage; and

assigning a specific address to said node based on the relative location of said node in the predetermined topology, by;

correlating the distance of said node to a predetermined node function;

wherein the specific address is related to said node function.

23. A method for initializing a distributed control system, the distributed control system having a control unit and at least one node coupled to a common bus, the distributed control system having a predetermined topology, the method comprising the steps of:

providing on the communication bus a reference current which increases with time to create a distance voltage at said node;

monitoring the distance voltage at said node;

when the distance voltage of said node reaches a trigger point, assigning an address to said node relative to a time at which the distance voltage measured at said node reaches the trigger point.

24. The method of claim 23, wherein the time identifies a relative position of said node in said topology.

25. The method of claim 23, wherein the time correlates a specific function to said node relative to other nodes in the predetermined topology.

26. The method of claim 23, further comprising the steps of:

providing a reference voltage on the communication bus;

measuring the reference voltage at said node to derive the trigger point; and

storing the trigger point within said node.

27. The method of claim 23, wherein the step of storing the trigger point is performed using a storage device in a sample-and-hold circuit.

28. The method of claim 23, the step of assigning comprising the step of:

using said node to alter an electrical characteristic of the communication bus to provide a signal to the control unit that the trigger point is reached in said node.

29. The method of claim 28, the step of assigning further comprising the steps of:

m response to receiving said signal, providing the specific address to said node; and

placing said node into a disabled state until address initialization is complete.

30. A node, adapted for use with a control unit in a distributed control system having a common bus, the node comprising:

analog distance determination circuitry adapted to be coupled to the bus to determine a location on the bus of the node relative to the control unit;

node control circuitry coupled to the analog distance determination circuitry and adapted to communicate with the control unit to provide said location to the control unit and to receive an address from the control unit.

31. The node of claim 30, further comprising:

communication circuitry coupled to the bus and to the node control circuitry and adapted to communicate with the control unit via the bus.

32. The node of claim 31, wherein both the communication circuitry and the analog distance determination circuitry are adapted to be coupled in common to the bus.

33. The node of claim 31, wherein both the communication circuitry and the analog distance determination circuitry are adapted to be coupled in common to the bus within said node.

34. The node of claim 30, wherein:

the analog distance determination circuitry comprises an analog-to-digital converter adapted to receive an analog voltage from the bus and provide a corresponding digital value; and

the node control circuitry is adapted to control the analog-to-digital converter during address initialization of the distributed control system.

35. The node of claim 34, further comprising:

communication circuitry coupled to the bus and to the node control circuitry and adapted to communicate with the control unit via the bus.

36. The node of claim 35, wherein both the communication circuitry and the analog distance determination circuitry are adapted to be coupled in common to the bus.

37. he node of claim 35, wherein both the communication circuitry and the analog distance determination circuitry are adapted to be coupled in common to the bus within said node.

38. The node of claim 30, further comprising:

a memory storage circuitry coupled to the node control circuitry and adapted to store said address.

39. The node of claim 30, further comprising:

actuator control circuitry coupled to the node control circuitry and adapted to selectively enable an actuator.

40. The node of claim 39, wherein said actuator control circuit enables said actuator in response to the communication circuitry receiving via said bus an actuation command addressed to said node.

41. The node of claim 40, wherein the actuator is adapted to activate at least one automotive airbag.

42. The node of claim 40, wherein the actuator is adapted to control an electric motor.

43. The node of claim 30, further comprising:

sensor control circuitry coupled to the node control circuitry and adapted to selectively enable a sensor.

44. The node of claim 43, wherein said sensor control circuitry enables said sensor in response to the communication circuitry receiving via said bus a sensor command addressed to said node.

45. The node of claim 43, wherein the sensor is adapted to sense acceleration.

46. The node of claim 43, wherein the sensor is adapted to sense an environmental parameter.

47. The node of claim 35, wherein the node includes an error checking unit coupled to the communication circuitry and adapted to make validity determinations of transmissions received via the bus.

48. A node, adapted for use with a control unit in a distributed control system having a common bus, the node comprising:

analog distance determination circuitry adapted to be coupled to the bus to determine a location on the bus of the node relative to the control unit, comprising;

sample-and-hold circuitry coupled to the bus and adapted to sample a reference voltage communicated across the bus and to hold said sampled voltage; and

voltage comparison circuitry coupled the bus and to the sample-and-hold circuitry and adapted to compare a distance voltage communicated on the bus to said sampled voltage;

node control circuitry coupled to the analog distance determination circuitry and adapted to communicate with the control unit to provide said location to the control unit and to receive an address from the control unit.

49. The node of claim 48, wherein the voltage comparison circuitry is further adapted to provide an identification signal when the distance voltage communicated on the bus approximately equals said sampled voltage.

50. The node of claim 49, wherein the node control circuitry is adapted to communicate with the control unit to provide said location to the control unit in response to the identification signal.

51. A distributed control system, comprising:

a first node;

a second node; and

a wire electrically coupling the first node and the second node, the wire having a length which is selected so that the resistivity of the wire between said first and second nodes exceeds a predetermined minimum resistivity wherein the physical distance between the first and second nodes is X. and, if the resistivity of a length X of said wire is below said minimum resistivity, the length of said wire is increased to a value Y such that the resistivity of said wire exceeds said minimum resistivity.

55. The method of claim 51, wherein the first node and the second node activate a same device.

56. The method of claim 55, wherein the first node activates the same device at a first speed and the second node activates the same device at a second speed, wherein the second speed is different from the first speed.

52. A method for finding relative locations of nodes to each other in a distributed control system, the distributed control system having a control unit and a communication bus coupled to the nodes, the distributed control system having a predetermined topology, the method comprising the steps of:

providing a signal to the nodes, the signal creating a measurement signal along a length of the communication bus where the measurement signal has a characteristic that is a function of distance of the measurement signal from the control unit along the communication bus; and

measuring the measurement signal at each node to create distance indicators, wherein the each of the distance indicators identifies a specific location for a respective node.

53. A controller in a distributed control system having at least one control element, the controller adapted to communicate via a common bus, the controller comprising:

a voltage developing circuit coupled to the common bus and adapted to develop a reference voltage on the common bus at the node, the voltage developing circuit adapted to develop incremental voltages on the common bus at the control element; and

a communication circuit coupled to the common bus, the communication circuit adapted to receive identification information from the node via the common bus, the communication circuit adapted to assign an address to the control element via the common bus.