System having devices connected via communication lines

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.

What is claimed is:  
     
         1 . A system in which a plurality of devices driven by supply of power are connected, 
 wherein each of at least two devices out of said devices comprises memory means for storing history information of each device under connection in the system, and control means for altering the history information in said memory means when an alteration occurs in a configuration of the system.    
     
     
         2 . A system according to  claim 1 , wherein each of said devices can be a primary host device having a primary host function or a secondary host device having a secondary host function, wherein when said primary host device is disconnected from connection in the system, said control means of the secondary host device sets the secondary host device 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 connection in the system, said control means of the primary host device designates another device as a new secondary host device.  
     
     
         3 . A system in which a plurality of devices driven by supply of power are connected, 
 wherein each of at least two devices out of said devices comprises memory means for storing history information of each device under connection in the system, and control means for altering the history information in said memory means when an alteration occurs in a configuration of the system and for performing such control that a total demanded power of said devices does not exceed a total supplied power.    
     
     
         4 . A system according to  claim 3 , wherein each of said 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 the primary host device is disconnected from connection in the system, said control means of the secondary host device sets the secondary host device 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 connection in the system, said 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 said 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 said devices is a device capable of supplying power to the other devices and wherein there are said device capable of supplying power and the devices receiving the power from the device capable of supplying power, mixed in the system.  
     
     
         7 . A system according to  claim 6 , wherein said device capable of supplying power is a primary host device.  
     
     
         8 . A system according to  claim 6 , wherein when an alteration occurs in the configuration of the system, said control means of said device capable of supplying power reports supplied power to a primary host device and said control means of said devices receiving the 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 when an alteration occurs in the configuration of the system, said control means of each said device notifies the control means of the other devices of its ID specific thereto and that it is a primary host device or a secondary host device, said control means of said device capable of supplying power reports supplied power thereof, and said control means of each said 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 control means of said 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 system according to  claim 4 , wherein when a device is disconnected from connection in the system, said control means of said primary host device deletes history information of said device from said memory means.  
     
     
         12 . A system according to  claim 4 , wherein when a device is added to connection in the system, said control means of said primary host device stores history information of said device in said memory means.  
     
     
         13 . A control method applied to a system in which a plurality of devices driven by supply of power are connected, 
 wherein each of at least two devices out of said devices has a memory step of storing history information of each device under connection in the system, and a control step of altering said history information when an alteration occurs in a configuration of the system.    
     
     
         14 . A control method according to  claim 13 , wherein each of said devices can be a primary host device having a primary host function or a secondary host device having a secondary host function, wherein when the primary host device is disconnected from connection in the system, said control step of the secondary host device comprises a step of setting the secondary host device itself 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 connection in the system, said control step of the primary host device comprises a step of designating another device as a new secondary host device.  
     
     
         15 . A control method applied to a system in which a plurality of devices driven by supply of power are connected, 
 wherein each of at least two devices out of said devices has a memory step of storing history information of each device under connection in the system, and a control step of altering said history information when an alteration occurs in a configuration of the system and performing such control that a total demanded power of said devices does not exceed a total supplied power.    
     
     
         16 . A control method according to  claim 15 , wherein each of said 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 the primary host device is disconnected from connection in the system, said control step of the secondary host device comprises a step of setting the secondary host device 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 connection in the system, said control step of the primary host device designates another device as a new secondary host device.  
     
     
         17 . A control method according to  claim 13 , wherein at least two devices out of said devices are a primary host device and a secondary host device.  
     
     
         18 . A control method according to  claim 13 , wherein at least one device out of said devices is a device capable of supplying power to the other devices and wherein there are said device capable of supplying power and the devices receiving the power from the device capable of supplying power, mixed in the system.  
     
     
         19 . A control method according to  claim 18 , wherein said device capable of supplying power is a primary host device.  
     
     
         20 . A control method according to  claim 18 , wherein an alteration occurs in the configuration of the system, said control step of said device capable of supplying power comprises a step of reporting supplied power to a primary host device and said control step of each said device receiving the power comprises a step of reporting consumed powers thereof in action and in a power saving mode to the primary host device.  
     
     
         21 . A control method according to  claim 18 , wherein when an alteration occurs in the configuration of the system, said control step of each said device comprises a step of notifying the other devices of its ID specific thereto and that it is a primary host device or a secondary host device, said control step of said device capable of supplying power comprises a step of reporting supplied power thereof, and said control step of each said device receiving the power comprises a step of reporting consumed powers thereof in action and in a power saving mode.  
     
     
         22 . A control method according to  claim 16 , wherein said control step of said primary host device 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 said memory means.  
     
     
         23 . A control method according to  claim 16 , wherein said control step of said primary host device comprises a step of deleting history information of a device from said memory means when said device is disconnected from connection in the system.  
     
     
         24 . A control method according to  claim 16 , wherein said control step of said primary host device comprises a step of storing history information of a device in said memory means when said device is added to connection in the system.  
     
     
         25 . A computer-readable memory medium storing a program for carrying out a history information succeeding method applied to a bus system to which a plurality of devices driven by supply of power can be connected, 
 wherein said history information succession method comprises a memory step of storing the history information of each device under connection to the system, and a control step of altering said history information when an alteration occurs in a configuration of the system.    
     
     
         26 . A computer-readable memory medium storing a program for carrying out a history information succeeding method applied to a bus system to which a plurality of devices driven by supply of power can be connected, 
 wherein said history information succession method comprises a memory step of storing the history information of each device under connection to the system, and a control step of altering said history information when an alteration occurs in a configuration of the system and performing such control that a total demanded power of said devices does not exceed a total supplied power.    
     
     
         27 . A power control apparatus for a driving device to which power is supplied from a power supplying device which is subject to current limitation at a predetermined current limit value, 
 said power control apparatus comprising a rechargeable battery, and a charge control part for charging said battery while a current drain is lower than said limit current value,    wherein when the current drain exceeds said limit current value, a current is supplied from said battery to said driving device.    
     
     
         28 . A power control apparatus according to  claim 27 , wherein said driving device is a device a current drain of which becomes transiently over said limit current value.  
     
     
         29 . A power control apparatus according to  claim 27 , wherein the power from said power supplying device is supplied via a USB connector.  
     
     
         30 . A USB apparatus comprising a driving device to which power is supplied from a power supplying device which is subject to current limitation at a predetermined current limit value, and a power control device connected to said power supplying device via a USB connector and arranged to control supply of the power to said driving device, 
 wherein said power control device comprises a rechargeable battery, and a charge control part for charging said battery while a current drain is lower than said limit current value, and wherein when the current drain exceeds said current limit value, a current is supplied from said battery to said driving device.    
     
     
         31 . A USB apparatus according to  claim 30 , wherein said driving device is a device a current drain of which becomes transiently over said limit current value.  
     
     
         32 . A USB apparatus according to  claim 31 , wherein said driving device is comprised of a speaker device incorporating a power amplifier.  
     
     
         33 . A USB apparatus according to  claim 31 , wherein said driving device is comprised of a floppy disk drive.  
     
     
         34 . A power control method for a driving device to which power is supplied from a power supplying device which is subject to current limitation at a predetermined current limit value, said power control method comprising steps of: 
 preparing a rechargeable battery;    charging said battery while a current drain is lower than said current limit value; and    supplying a current from said battery to said driving device when the current drain exceeds said limit current value.    
     
     
         35 . A power control method according to  claim 34 , wherein said driving device is a device a current drain of which becomes transiently over said limit current value.  
     
     
         36 . An information processing apparatus comprising: 
 means for distributing upstream bus means serially connected to an upstream device, to downstream bus means serially connected to a plurality of downstream devices,    wherein when energization from said upstream bus means is present, data from the upstream device is transmitted to said downstream bus means and wherein when the energization from said upstream bus means is absent, said means is connected to an image input/output device connected to said downstream bus means to effect transfer of image data thereto or therefrom.    
     
     
         37 . An information processing apparatus according to  claim 36 , wherein a control program for controlling said image input/output device is received from an external device and the transfer of the image data to or from said image input/output device is carried out according to the control program thus received.  
     
     
         38 . An information processing apparatus according to  claim 37 , wherein when the energization from said upstream bus means is present, said control program is received from the external device and wherein when the energization from said upstream bus means is absent, the transfer of the image data to or from said image input/output device is carried out according to the control program received from said external device.  
     
     
         39 . An information processing apparatus according to  claim 38 , further comprising a memory for storing said control program and detection means for detecting presence/absence of the control program in said memory, 
 wherein when the control program is not stored in said memory, the transfer of the image data to or from said image input/output device is carried out according to the control program received from said external device.    
     
     
         40 . An information processing apparatus according to  claim 36 , wherein a control program for controlling said image input/output device is received from said image input/output device and the transfer of the image data to or from said image input/output device is carried out according to the control program thus received.  
     
     
         41 . A display control method comprising steps of: 
 preparing means for distributing upstream bus means under one-to-one serial connection to an upstream device, to downstream bus means under one-to-one serial connection to a plurality of downstream devices;    transmitting data from the upstream device to said downstream bus means when energization from said upstream bus means is present;    connecting said means to an image input/output device connected to said downstream bus means to effect transfer of image data thereto or therefrom when the energization from said upstream bus means is absent; and    displaying said image data on a display.    
     
     
         42 . A display control method according to  claim 41 , wherein a control program for controlling said image input/output device is received from an external device and the transfer of the image data to or from said image input/output device is carried out according to the control program thus received.  
     
     
         43 . A display control method according to  claim 42 , wherein when the energization from said upstream bus means is present, said control program is received from the external device and wherein when the energization from said upstream bus means is absent, the transfer of the image data to or from said image input/output device is carried out according to the control program received from said external device.  
     
     
         44 . A display control method according to  claim 42 , further comprising a memory for storing said control program and detection means for detecting presence/absence of the control program in said memory, 
 wherein when the control program is not stored in said memory, the transfer of the image data to or from said image input/output device is carried out according to the control program received from said external device.    
     
     
         45 . A display control method according to  claim 41 , wherein a control program for controlling said image input/output device is received from said image input/output device and the transfer of the image data to or from said image input/output device is carried out according to the control program thus received.  
     
     
         46 . A memory medium storing a program capable of being read by a computer, which executes a display control method with means for distributing upstream bus means under one-to-one serial connection to one upstream device, to downstream bus means under one-to-one serial connection to a plurality of downstream devices, for connecting said means to an image input/output device connected to said downstream bus means and displaying image data thereof on a display, comprising steps of: 
 detecting energization from said upstream bus means;    transferring data from the upstream device to said downstream bus means when the energization from said upstream bus means is present, and connecting said means to the image input/output device connected to said downstream bus means to effect transfer of the image data thereto or therefrom when the energization from said upstream bus means is absent; and    displaying said image data on the display.