System having devices connected via communication lines

• US 6,715,071 B2
• Filed: 06/25/1999
• Issued: 03/30/2004
• Est. Priority Date: 06/26/1998
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Nakajima, Tatsuya, Ono, Kenichiro, Shibamiya, Yoshikazu
• Primary Examiner(s): Myers, Paul R.
• Application Number:
  US09/344,509
• Publication Number:
  US 20030088798A1
• Time in Patent Office: 1,740 Days
• Field of Search: 710/302, 710/304, 710/104, 710/10, 713/1, 713/2, 713/100
• US Class Current: 713/100
• CPC Class Codes: G06F 1/266 Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips

Abstract

Log information disappears when a host device storing the log information, which is histories of respective devices under connection, is disconnected. Further, when USB or the like is used as an interface bus, supplied power has to be limited with consideration to the load on the power supply of the host device.

Therefore, here is a proposal of a system that permits succession of the history information of each device even if any device is disconnected and that permits efficient utilization of power.

Claims

1. A system in which a plurality of devices driven by supply of power are connected, each of at least two devices out of the plurality of devices comprising:

memory means for storing common history information of each device connected to said system; and

first control means for altering, when the present device configuration of said system is altered to a new device configuration, the common history information of the present device configuration in all of said memory means to new common history information reflecting the new device configuration.

2. A system according to claim 1, wherein each of said at least two devices can be a primary host device having a primary host function or a secondary host device having a secondary host function,

wherein, when one of said at least two devices is serving as the primary host and the other of said at least two devices is serving as the secondary host and the primary host device is disconnected from the system, said first control means of the secondary host device sets the secondary host device as a new primary host device, and

wherein, when the secondary host device is disconnected from the system, said first control means of the primary host device designates another device as a new secondary host device.

3. A system according to claim 1, wherein each of said at least two devices further comprises second control means for controlling a total demanded power of the plurality of devices so that the total demanded power does not exceed a total supplied power.

4. A system according to claim 3, wherein each of said at least two devices can be a primary host device having a primary host function or a secondary host device having a secondary host function and can transfer into a power saving mode,

wherein, when one of said at least two devices is serving as the primary host and the other of said at least two devices is serving as the secondary host and the primary host device is disconnected from the system, said first control means of the secondary host device sets itself as a new primary host device and designates another device as a new secondary host device, and

wherein, when the secondary host device is disconnected from the system, said first control means of the primary host device designates another device as a new secondary host device.

5. A system according to claim 1, wherein at least two devices out of the plurality of devices are a primary host device and a secondary host device.

6. A system according to claim 1, wherein at least one device out of the plurality of devices is a device capable of supplying power to the other devices, and

wherein there are, mixed in the system, the device capable of supplying power and devices receiving the power from the device capable of supplying power.

7. A system according to claim 6, wherein the device capable of supplying power is a primary host device.

8. A system according to claim 6, wherein the device capable of supplying power and the devices receiving the supplied power comprise first control means for altering history information in a memory means when a configuration of the system is altered, wherein, when the configuration of the system is altered, said first control means of the device capable of supplying power reports supplied power to a primary device and said first control means of the devices receiving the supplied power reports consumed powers thereof in action and in a power saving mode to the primary host device.

9. A system according to claim 6, wherein each of the plurality of devices comprises a first control means for storing history information in a memory means when a configuration of the system is altered, wherein, when the configuration of the system is altered, said first control means of each of the plurality devices notifies the first control means of the other devices of its specific ID and that it is a primary host device or a secondary host device, said first control means of said device capable of supplying power reports supplied power thereof, and said first control means of each device receiving the power reports consumed powers thereof in action and in a power saving mode.

10. A system according to claim 4, wherein said first control means of the primary host device gives a command for entry into the power saving mode to a device of a shorter active time than others, based on the history information in said memory means.

11. A control method applied to a system in which a plurality of devices driven by supply of power are connected, comprising:

a memory step of storing common history information of each device connected to the system in memory means of at least two devices out of the plurality of devices; and

a first control step of altering, when the present device configuration of the system is altered to a new device configuration, the common history information of the present device configuration in all of the memory means to new common history information reflecting the new device configuration.

12. A control method according to claim 11, wherein each of the at least two devices can be a primary host device having a primary host function or a secondary host device having a secondary host function,

wherein, when one of the at least two devices is serving as the primary host and the other of the at least two devices is serving as the secondary host and the primary host device is disconnected from the system, said first control step comprises a step of setting the secondary host device as a new primary host device and designating another device as a new secondary host device, and

wherein, when the secondary host device is disconnected from the system, said first control step comprises a step of designating another device as a new secondary host device.

13. A control method according to claim 11, further a comprising a second control step of controlling a total demanded power of the plurality of devices so that the total demanded power does not exceed a total supplied power.

14. A control method according to claim 13, wherein each of the at least two devices can be a primary host device having a primary host function or a secondary host device having a secondary host function and can transfer into a power saving mode,

wherein, when one of the at least two devices is serving as the primary host and the other of the at least two devices is serving as the secondary host and the primary host device is disconnected from the system, said first control step comprises a step of setting the secondary host device as a new primary host device, and

wherein, when the secondary host device is disconnected from the system, said first control step designates another device as a new secondary host device.

15. A control method according to claim 14, wherein said first control step comprises a step of giving a command for entry into the power saving mode to a device of a shorter active time than others, based on the history information in the memory means.

16. A computer-readable memory medium storing a program for controlling a system in which a plurality of devices driven by supply of power are connected, comprising:

a memory step of storing common history information of each device connected to the system in memory means of at least two devices out of the plurality of devices; and

a first control step of altering, when the present device configuration of the system is altered to a new device configuration, the history information of the present device configuration in all of the memory means to new common history information reflecting the new device configuration.

17. A computer-readable memory medium according to claim 16, further comprising a second control step of controlling a total demanded power of the devices so that the total demanded power does not exceed a total supplied power.