Failsafe switching of intelligent controller method and device

• US 20060025871A1
• Filed: 09/23/2004
• Published: 02/02/2006
• Est. Priority Date: 07/27/2004
• Status: Active Grant

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: MKS Instruments Incorporated
• Inventors: Hadar, Ron, Lev-Ami, Uzi, Sifnatsch, Guenter, Khalil, Nidal
• Granted Patent: US 7,219,255 B2
• Time in Patent Office: Days
• US Class Current: 700/21
• CPC Class Codes: G05B 9/03 with multiple-channel loop, i.e. redundant control systems

Abstract

The present invention relates to control of and data collection from sensors associated with tools. In particular, it relates to using a controller to mediate communications among a tool, sensors associated with the tool and data users, such as a host system or distributed processors. Particular aspects of the present invention are described in the claims, specification and drawings.

Claims

1. A method of transparently establishing connection between first and second devices, in case of failure of an intermediate device, the method including:

connecting the first and second devices to first and second network interfaces of an intermediate device, the first and second network interfaces having data link layer identifiers that are distinct from those associated with the first or second devices;

in a normal operating mode, handling the intermediate device messages addressed between the first and second devices, while the intermediate device repeatedly signals to a failsafe switch its continuing healthy operation; and

at the failsafe switch, upon interruption of the repeated signals of healthy operation from the intermediate device, switching to a failsafe mode by directly connecting the first and second devices with a data connection that bypasses the intermediate device.

2. The method of claim 1, wherein switching the failsafe switch to failsafe mode includes making an audible signal.

3. The method of claim 2, wherein the audible signal is a relay click.

4. The method of claim 1, wherein the first and second network interfaces are adapted to pass all packets received to a filter that retains for processing packets addressed to the intermediate device.

5. The method of claim 1, wherein the handling of packets includes, for at least some packets, relaying the packets from the first or second device to the second or first device and specifying in a source identification field of the relayed packets a data link layer identifier of the actual source, instead of a data link identifier of the first or second network interface.

6. The method of claim 1, wherein repeatedly signaling continuing health is implemented by a daemon running on the intermediate device that sends a message to the failsafe switch.

7. The method of claim 1, wherein repeatedly signaling continuing health is implemented by a daemon running on the intermediate device that listens for and responds to inquiries from the failsafe switch.

8. The method of claim 1, further including a plurality of second devices connecting to the first device using a single physical communications links.

9. The method of claim 8, wherein the single physical communications link is an Ethernet segment.

10. The method of claim 1, further including a plurality of second devices connecting to the first device using a two or more physical communications links.

11. The method of claim 10, wherein one of the physical communications links is an Ethernet segment and another is a serial connection.

12. The method of claim 11, wherein the serial connection complies with an RS-232 or RS-422 standard.

13. The method of claim 1, wherein establishing a direct communications session between the first and second devices does not require updating in the first or second devices any tables correlating network addresses and data link layer addresses.

14. The method of claim 1, wherein network addresses of the first and second devices and the intermediate device all are within the same network subnet.

15. The method of claim 1, wherein establishing a direct communications session between the first and second devices does not require updating in the first or second devices any tables correlating IP and MAC addresses.

16. A fail-over method of establishing a communications link between a host and a tool after failure of an intelligent controller coupled between the host and the tool, the method including:

adopting at a first port of the intelligent controller a first hardware-level identifier otherwise used by the tool and advertising the first port to the host as being addressed using the first hardware-level identifier;

adopting at a second port of the intelligent controller a second hardware-level identifier otherwise used by the host and advertising the second port to the tool as being addressed using the second hardware-level identifier;

intercepting at the intelligent controller advertisements of the first and second hardware-level identifiers, so that the host and the tool are not in direct advertising communication;

repeatedly signaling a failsafe switch that the intelligent controller should be relied upon, wherein the failsafe switch is adapted upon failure of the repeated signaling to directly connect the host and the tool with a communications link that bypasses the intelligent controller, whereby the host and the tool are in direct advertising communication and the advertisements of the first and second hardware-level identifiers facilitate establishment of the communications link between the host and the tool.

17. The method of claim 16, wherein a first logical IP address identifying the first port, a second logical IP address used by the tool, a third logical IP address identifying the second port and a fourth logical IP address used by the host are all different.

18. The method of claim 16, wherein a first logical network-layer address identifying the first port, a second logical network-layer address used by the tool, a third logical network-layer address identifying the second port and a fourth logical network-layer address used by the host are all different.

19. The method of claim 16, wherein the hardware-level identifier is a MAC address.

20. The method of claim 16, wherein the advertisements of the hardware-level identifiers are by standard-compliant ARP messages.

21. The method of claim 16, further applied to a sensor that monitors the tool, wherein the intelligent controller is coupled between the host and the sensor, the method further including:

adopting at the first port of the intelligent controller a third hardware-level identifier otherwise used by the sensor and advertising the first port to the host as being addressed using the third hardware-level identifier;

advertising the second port to the sensor as being addressed using the second hardware-level identifier; and

intercepting at the intelligent controller advertisements of the third hardware-level identifier, so that the host and the sensor are not in direct advertising communication;

wherein the failsafe switch upon failure of the repeated signaling establishes a direct communications link between the host and the sensor that bypasses the intelligent controller.

22. The method of claim 21, wherein a first logical IP address identifying the first port, a second logical IP address used by the tool, a third logical IP address identifying the second port, a fourth logical IP address used by the host and a fifth logical IP address used by the sensor are all different.

23. The method of claim 21, wherein a first logical network-layer address identifying the first port, a second logical network-layer address used by the tool, a third logical network-layer address identifying the second port, a fourth logical network-layer address used by the host and a fifth logical network-layer address used by the sensor are all different.

24. The method of claim 21, wherein the hardware-level identifier is a MAC address.

25. The method of claim 21, wherein the advertisements of the hardware-level identifiers are by standard-compliant ARP messages.

26. A method of introducing a fail-over protected intelligent controller and switch into a communications link between a host coupled to at least one tool, the method including:

coupling the switch to the host, the intelligent controller and the tool, wherein the host and the tool communicate with the intelligent controller and not directly with each other when the switch is in a first state and the host and the tool communicate directly with each other when the switch is in a second state;

in the first state, the intelligent controller

intercepting messages between the host and tool,

modifying at least one hardware-level source identifier and at least one hardware-level destination identifier in the intercepted messages,

modifying at least one error correction code in the intercepted messages to correspond to the modified hardware-level identifiers, and

relaying the intercepted messages with the modified hardware-level identifiers and the modified correction code; and

in the second state, the switch bypassing the intelligent controller, whereby the host communicates directly with the tool.

27. The method of claim 26, wherein

the intelligent controller includes at least a first port and a second port, the first port coupled in communication with the host and the second port coupled in communication with the tool;

and

a first logical IP address identifying the first port, a second logical IP address used by the tool, a third logical IP address identifying the second port and a fourth logical IP address used by the host are all different.

28. The method of claim 26, wherein

the intelligent controller includes at least a first port and a second port, the first port coupled through the switch in communication with the host and the second port coupled through the switch in communication with the tool;

and

a first logical network-layer address identifying the first port, a second logical network-layer address used by the tool, a third logical network-layer address identifying the second port and a fourth logical network-layer address used by the host are all different.

29. The method of claim 26, wherein the hardware-level identifier is a MAC address.

30. The method of claim 26, further applied to at least one sensor that monitors the tool, the method further including:

coupling the failsafe switch to the sensor, wherein the host and sensor communicate with the intelligent controller and not directly with each other when the failsafe switch is in the first state and the host and the sensor communicate directly with each other when the failsafe switch is in the second state;

in the first state, the intelligent controller

intercepting messages between the host and sensor,

modifying at least one hardware-level source identifier and at least one hardware-level destination identifier in the intercepted messages,

modifying at least one error correction code in the intercepted messages to correspond to the modified hardware-level identifiers, and

relaying the intercepted messages with the modified hardware-level identifiers and the modified correction code; and

in the second state, the failsafe switch bypassing the intelligent controller, whereby the host communicates directly with the sensor.

31. The method of claim 30, wherein

the intelligent controller includes at least a first port and a second port, the first port coupled through the failsafe switch in communication with the host and the second port coupled through the failsafe switch in communication with the tool and the sensor;

and

a first logical IP address identifying the first port, a second logical IP address used by the tool, a third logical IP address identifying the second port, a fourth logical IP address used by the host and a fifth logical IP address used by the sensor are all different.

32. The method of claim 30, wherein

the intelligent controller includes at least a first port and a second port, the first port coupled through the failsafe switch in communication with the host and the second port coupled through the failsafe switch in communication with the tool and the sensor;

and

a first logical network-layer address identifying the first port, a second logical network-layer address used by the tool, a third logical network-layer address identifying the second port, a fourth logical network-layer address used by the host and a fifth logical network-layer address used by the sensor are all different.

33. The method of claim 30, wherein

the intelligent controller includes at least a first port, a second port and a third, the first port coupled through the failsafe switch in communication with the host, the second port coupled through the failsafe switch in communication with the tool and the third port coupled through the failsafe switch in communication with the sensor;

and

a first logical IP address identifying the first port, a second logical IP address used by the tool, a third logical IP address identifying the second port, a fourth logical IP address used by the host and a fifth logical IP address used by the sensor are all different.

34. The method of claim 30, wherein

the intelligent controller includes at least a first port, a second port and a third, the first port coupled through the failsafe switch in communication with the host, the second port coupled through the failsafe switch in communication with the tool and the third port coupled through the failsafe switch in communication with the sensor;

and

a first logical network-layer address identifying the first port, a second logical network-layer address used by the tool, a third logical network-layer address identifying the second port, a fourth logical network-layer address used by the host and a fifth logical network-layer address used by the sensor are all different.

35. An intermediate device with failsafe switch adapted to assure direct connection between first and second devices, in case of failure of an intermediate device, the method including:

an intermediate device having first and second network interfaces that are linked in communication with the first and second devices, respectively, the first and second network interfaces having data link layer identifiers that are distinct from any data link layers identifiers associated with the first or second devices;

a failsafe switch in communication with the intermediate device and contingently linked in communication with the first and second devices, wherein the failsafe switch is adapted to a normal operation mode in which the first and second devices communicate with the first and second network interfaces and a failsafe operation mode in which the first and second devices communicate directly, bypassing the intermediate device;

logic and resources on the intermediate device adapted to repeatedly communicate healthy operation of the intermediate device to the failsafe switch;

logic and resources on the failsafe switch adapted to respond to interruption of the repeated signals of healthy operation from the intermediate device by switching to a failsafe mode.

36. The intermediate device and failsafe switch of claim 35, wherein switching the failsafe switch to failsafe mode further includes making an audible signal.

37. The intermediate device with failsafe switch of claim 36, wherein the audible signal is a relay click.

38. The intermediate device with failsafe switch of claim 35, wherein the logic and resources of the intermediate device further include a filter that retains for processing packets addressed to the intermediate device, the filter being coupled to the first and second network interfaces.

39. The intermediate device with failsafe switch of claim 35, wherein the logic and resources of the intermediate device further include a daemon running on the intermediate device that sends a message to the failsafe switch.

40. The intermediate device with failsafe switch of claim 35, wherein the logic and resources of the intermediate device further include a daemon running on the intermediate device that listens for and responds to inquiries from the failsafe switch.