Method and apparatus for optimizing communications in a multiplexer network

• US 7,054,337 B2
• Filed: 03/15/2002
• Issued: 05/30/2006
• Est. Priority Date: 03/15/2002
• Status: Active Grant

• Current Assignee: Fisher Controls International LLC (Emerson Electric Company)
• Original Assignee: Fisher Controls International LLC (Emerson Electric Company)
• Inventors: Jackson, Alfred Russell III
• Primary Examiner(s): Ho, Duc
• Application Number:
  US10/099,575
• Publication Number:
  US 20030174738A1
• Time in Patent Office: 1,537 Days
• Field of Search: None
• US Class Current: 370/535
• CPC Class Codes: H04L 1/1883 using multiple timers
• CPC Class Codes: H04L 1/189 Transmission or retransmission of more than one copy of a message

Abstract

An apparatus for optimizing multiplexer communications in a system having a host, a multiplexer, and a field instrument device. The host is arranged to run a host software and to transmit a message to the multiplexer, the message including an embedded message for the instrument device. The host re-transmits the message until a response to the message is received from the device via the multiplexer, with the first re-transmission occurring after a long delay and a second and all subsequent re-transmissions occurring after a second time interval. An optimizing controller is arranged to establish a count indicating the number of re-transmissions occurring before the response has been communicated to the host, assess a message turnaround time based on the communication time it takes to transmit the message from the host to the multiplexer and to transmit the response from the multiplexer to the host, establish a bracket width at least as long as the message turnaround time, establish a short delay, and vary at least one of the long delay and the short delay to minimize the count.

Claims

1. An apparatus for optimizing multiplexer communications comprising:

a host;

a multiplexer; and

an instrument device;

the host arranged to run a host software and to send a first message and a plurality of subsequent messages to the multiplexer, each of the messages including an embedded message for the instrument device, the time period between the first message and a first subsequent message defining a long delay;

the multiplexer arranged to strip the embedded message and to forward the embedded message to the instrument device, the multiplexer further arranged to send a response to the host, the response indicative of whether the embedded message has been forwarded to the multiplexer and whether a reply has been received from the instrument device, the multiplexer further arranged to receive and store the reply;

the instrument device arranged to receive and process the embedded message and to send the reply to the multiplexer; and

an optimizing controller operatively coupled to the host, the optimizing controller arranged to;

communicate to the host whether the reply has been received by the multiplexer;

establish a count, the count indicating the number of subsequent messages occurring before the reply has been received by the multiplexer;

assess a message turnaround time, the message turnround time based on the time it takes to transmit any one of the messages to the multiplexer and to receive the response from the multiplexer;

establish a bracket width, the bracket width at least as long as the message turnaround time;

establish a short delay based at least in part on the message turnaround time and the bracket width; and

vary at least one of the long delay and the short delay to minimize the count.

2. The apparatus of claim 1, wherein the optimizing controller is arranged to vary both the long delay and the short delay to minimize the count.

3. The apparatus of claim 1, wherein the multiplexer includes a buffer for storing the reply until the response is communicated to the host, and wherein the optimizing controller is further arranged to vary at least one of the long delay and the short delay to minimize a dead time period the reply resides in the buffer prior to retrieval by the host.

4. The apparatus of claim 1, wherein the optimizing controller is further arranged track a dead time, the dead time indicative of how long the response resides at the multiplexer prior to communication to the host, and wherein the optimizing controller is arranged to vary at least one of the long delay and the short delay to minimize the dead time.

5. The apparatus of claim 4, wherein the optimizing controller is arranged to vary both the long delay and the short delay to minimize the dead time.

6. The apparatus of claim 1, wherein the first message and the plurality of subsequent messages are chosen from a message set, the message set including a plurality of possible messages, each message in the message set having unique message parameters, and wherein the host is arranged to select a chosen message from the message set, and further wherein the optimizing controller is arranged to assess the unique message parameters of the chosen message and to establish the bracket width and the long delay based on the unique message parameters of the chosen message.

7. The apparatus of claim 6, wherein the instrument device includes a communication characteristic, and wherein the optimizing controller is arranged assess the communication characteristic and to vary the long delay and the short delay based at least in part on the communication characteristic.

8. The apparatus of claim 1, wherein the first message and the plurality of subsequent messages are chosen from a message set, the message set including a plurality of possible messages for the instrument device, each message in the message set having unique message parameters, and wherein the host is arranged to select a chosen message from the message set, and further wherein the optimizing controller is arranged to assess the message turnaround time for each message on the message set and establish the bracket width based on the greatest message turnaround time in the message set.

9. The apparatus of claim 1, wherein the receipt of the response by the host defines a complete message cycle, and wherein the optimizing controller is arranged to run an optimization cycle, the optimization cycle defined by lengthening the long delay to reach an optimization eligible state, the optimization eligible state defined by completion of the communication cycle with no more than two subsequent messages, the optimization cycle comprising shortening the long delay until a fail point is reached, the fail point defined by the sending of a third subsequent message.

10. The apparatus of claim 9, wherein the optimizing controller is arranged to re-run the optimization cycle after the fail point is reached.

11. An apparatus for optimizing multiplexer communications comprising:

a host;

a multiplexer; and

an instrument device;

the host arranged to run a host software and to transmit a message to the multiplexer, the message including an embedded message for the instrument device, the host arranged to re-transmit the message until a response to the message is received from the multiplexer, a first re-transmission occurring after a long delay, a second and all subsequent re-transmissions occurring after a second time interval;

the multiplexer arranged to strip the embedded message and to forward the embedded message to the instrument device, the multiplexer further arranged to indicate to the host whether the embedded message has been received and forwarded to the instrument device and whether the response has been received from the instrument device, the multiplexer further arranged to receive and store the reply until the reply is communicated to the host;

the instrument device arranged to receive and process the embedded message and to communicate the response to the multiplexer; and

an optimizing controller, the optimizing controller arranged to;

establish a count, the count indicating the number of re-transmissions occurring before the response has been communicated to the host;

assess a message turnaround time, the message turnround time based on the communication time it takes to transmit the message from the host to the multiplexer and to transmit the response from the multiplexer to the host;

establish a bracket width, the bracket width at least as long as the message turnaround time;

establish a short delay, the short delay based at least in part on the bracket width and the message turnaround time; and

vary at least one of the long delay and the short delay to minimize the count.

12. The apparatus of claim 11, wherein the multiplexer includes a buffer arranged to store the reply until the response is communicated to the host, and wherein the optimizing controller is further arranged to vary at least one of the long delay and the short delay to minimize a dead time, the dead time indicative of how long the response resides in the buffer prior to communication to the host.

13. The apparatus of claim 12, wherein the optimizing controller is further arranged to vary both of the long delay and the short delay to minimize the dead time.

14. The apparatus of claim 11, wherein the time indicative of how long the response resides at the multiplexer prior to communication to the host is indicated by a dead time, and wherein the optimizing controller is arranged to vary the long delay and the short delay to minimize the dead time.

15. The apparatus of claim 11, wherein the optimizing controller is arranged to vary both the long delay and the short delay to minimize the count.

16. The apparatus of claim 11, wherein the first message and the plurality of subsequent messages are chosen from a message set, the message set including a plurality of possible messages, each message in the message set having unique message parameters, and wherein the host is arranged to select a chosen message from the message set, and further wherein the optimizing controller is arranged to assess the unique message parameters of the chosen message and to establish the bracket width and the long delay based on the unique message parameters of the chosen message.

17. The apparatus of claim 16, wherein the instrument device includes a communication characteristic, and wherein the optimizing controller is arranged assess the communication characteristic and to vary the long delay and the short delay based at least in part on the communication characteristic.

18. The apparatus of claim 11, wherein the first message and the plurality of subsequent messages are chosen from a message set, the message set including a plurality of possible messages for the instrument device, each message in the message set having unique message parameters, and wherein the host is arranged to select a chosen message from the message set, and further wherein the optimizing controller is arranged to assess the message turnaround time for each message on the message set and establish the bracket width based on the greatest message turnaround time in the message set.

19. The apparatus of claim 11, wherein the receipt of the response by the host defines a complete message cycle, and wherein the optimizing controller is arranged to run an optimization cycle, the optimization cycle defined by lengthening the long delay to reach an optimization eligible state, the optimization eligible state defined by completion of the communication cycle with no more than two subsequent messages, the optimization cycle comprising shortening the long delay until a fail point is reached, the fail point defined by the sending of a third subsequent message.

20. The apparatus of claim 19, wherein the optimizing controller is arranged to re-run the optimization cycle after the fail point is reached.

21. A method for optimizing communications between a host, a multiplexer, and a field instrument device comprising:

providing a host controller;

providing a multiplexer; and

providing a field instrument device;

providing a host software for the host controller, the host software arranged to transmit a message to the multiplexer, the message including an embedded message for the instrument device, the host arranged to re-transmit the message until a response to the message is received from the multiplexer, a first re-transmission occurring after a long delay, a second and all subsequent re-transmissions occurring after a second time interval;

arranging the multiplexer to strip the embedded message and to forward the embedded message to the instrument device, the multiplexer further arranged to indicate to the host whether the embedded message has been received and forwarded to the instrument device and whether the response has been received from the instrument device;

the instrument device arranged to receive and process the embedded message and to communicate the response to the multiplexer; and

arranging the host controller to run an optimizing routine, the optimizing routine including;

establishing a count, the count indicating the number of re-transmissions occurring before the response has been communicated to the host;

assessing a message turnaround time, the message turnround time based on the communication time it takes to transmit the message from the host to the multiplexer and to transmit the response from the multiplexer to the host;

establishing a bracket width, the bracket width at least as long as the message turnaround time;

establishing a short delay based on the message turnaround time and the bracket width; and

varying at least one of the long delay and the short delay to minimize the count.

22. The method of claim 21, including providing the multiplexer with a buffer arranged to store the reply until the response is communicated to the host, and arranging the host controller to vary at least one of the long delay and the short delay to minimize a dead time, the dead time indicative of how long the response resides in the buffer prior to communication to the host.

23. The method of claim 22, wherein the optimizing controller is further arranged to vary both of the long delay and the short delay to minimize the dead time.

24. The method of claim 21, wherein the time the response resides in the buffer before being retrieved by the host is indicated by a dead time, and wherein the optimizing controller is arranged to vary the long delay and the short delay to minimize the dead time.

25. The method of claim 21, wherein the optimizing controller is arranged to vary both the long delay and the short delay to minimize the count.

26. The method of claim 21, wherein the first message and the plurality of subsequent messages are chosen from a message set, the message set including a plurality of possible messages, each message in the message set having unique message parameters, and wherein the host is arranged to select a chosen message from the message set, and further wherein the optimizing controller is arranged to assess the unique message parameters of the chosen message and to establish the bracket width and the long delay based on the unique message parameters of the chosen message.

27. The method of claim 26, wherein the instrument device includes a communication characteristic, and wherein the optimizing controller is arranged assess the communication characteristic and to vary the long delay and the short delay based at least in part on the communication characteristic.

28. The method of claim 21, wherein the first message and the plurality of subsequent messages are chosen from a message set, the message set including a plurality of possible messages for the instrument device, each message in the message set having unique message parameters, and wherein the host is arranged to select a chosen message from the message set, and further wherein the optimizing controller is arranged to assess the message turnaround time for each message on the message set and establish the bracket width based on the greatest message turnaround time in the message set.

29. The method of claim 21, wherein the receipt of the response by the host defines a complete message cycle, and wherein the optimizing controller is arranged to run an optimization cycle, the optimization cycle defined by lengthening the long delay to reach an optimization eligible state, the optimization eligible state defined by completion of the communication cycle with no more than two subsequent messages, the optimization cycle comprising shortening the long delay until a fail point is reached, the fail point defined by the sending of a third subsequent message.

30. The method of claim 29, wherein the optimizing controller is arranged to re-run the optimization cycle after the fail point is reached.

31. The method of claim 29, wherein the optimizing controller re-runs the optimization cycle after the fail point is reached, and wherein the optimizing controller is arranged to increase the long delay by a time period equal to about 25% of the bracket width prior to re-running the optimization cycle.

32. The method of claim 29, including storing data unique to at least one of a particular message, a particular field device, and a particular multiplexer.