Abstract:
An interface module for interfacing an external device with a host computer is physically and electrically connected to the host computer. The module monitors its own power consumption and reports its power consumption to the host computer. This information can be used to determine the total power consumed by multiple modules, to indicate a problem with the interface module, or to detect a leakage current associated with the external device when main power is off.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to computers and, more particularly, to interface modules for computers. In this specification, related art labeled “prior art” is admitted prior art; related art not labeled “prior art” is not admitted prior art.  
         [0002]     Computers are often built using interface modules, such as external disk interfaces that are inserted into peripheral connect interface (PCI) slots and PCI express slots. The modular nature makes it easy to repair and upgrade systems by swapping interface modules.  
       SUMMARY OF THE INVENTION  
       [0003]     The present invention as defined in the claims provides for tracking power consumption by interface modules. For example, an interface module within a computer system (such as a server) can actively monitor its own power consumption. The interface module can then report or maintain power-consumption data that may be accessed as needed by the computer system itself. “Module” herein refers to a device, such as a PCI card, a PMCIA Card, or a USB flash card adapter, that can be inserted and removed from a computer. “Interface module” refers to such modules that provide for communication between a computer and an external device.  
         [0004]     The invention allows accurate monitoring of conditions that could otherwise lead to failure and provides a source of diagnostic data in the event of system failure related to excessive power consumption. Modules that self-monitor power consumption can provide highly accurate data to the user and/or the system, which has significant advantages over error-prone theoretical measurements or estimations. In addition, certain embodiments of the invention provide for monitoring leakage currents, thereby providing for more reliable “hot-swapping” of interface modules. These and other features and advantages of the invention are apparent from the description below with reference to the following drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a schematic diagram of one of many interface modules within the scope of the invention.  
         [0006]      FIG. 2  is a flow chart of one of many methods within the scope of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0007]     Of the many possible interface modules provided by the invention,  FIG. 1  schematically represents an interface module AP 1  comprising a printed circuit board  11 , a plug  13 , a connector  15  for an external device  17 , interface circuitry  19 , a power sensor  21 , and a power tracker  23 . Plug  13  provides for physical and electrical connection with an incorporating host computer system  25 , e.g., via a socket fixed to motherboard thereof. Host computer system  25  can be a server, but the invention applies as well to other types of computers with modular interface devices.  
         [0008]     The electrical connections include power, ground, and signal lines, e.g., address, data, and control lines. Both main power  27  and a standby power  29  are supplied, as is ground  31 . More generally, several power lines at different voltage levels can be provided. A device data bus  33  provides various signal lines for interfacing with external device  17 . In addition, a power data bus  35  provides for communication between power tracker  23  and host system  25 .  
         [0009]     A method M 1  of the invention can be practiced in the context of interface module AP 1 , as well as in alternative modular interfaces. At process segment S 11 , interface module AP 1  is activated. Activation of module AP 1  can be the result of a power-on of host system  25 , or the supply of main power  27  to interface module AP 1 , e.g., after a hot swap.  
         [0010]     During process segment S 12 , power sensor  21  tracks power usage, e.g., by monitoring electrical parameters associated with main power  27  and ground  31 . Optionally, standby power  29  can be monitored. More generally, multiple power and ground sources can be monitored using sensor  21 . Sensor  21  converts analog sensor readings to digital form for transmission to power tracker  23 .  
         [0011]     At process segment S 13 , power tracker  23  analyzes and manipulates digital sensor data generated at process segment S 12 . For example, the data can be time-stamped and associated with other data, such as operating modes. If the data indicates a problematic condition, power tracker  23  can issue a warning along power data bus  35  to host computer system  25  at process step S 14 .  
         [0012]     At process segment S 15 , the modified power data can be stored in on-board non-volatile memory for future access by software running on host system  25 . To avoid overflowing the non-volatile memory, host computer software can read the contents at a process segment S 16  and, if appropriate, store it in more capacious memory, e.g., a hard disk. Alternatively, the modified power data can be streamed to host system  25 .  
         [0013]     Occasionally, a need may arise to remove interface module AP 1 . For example, interface module AP 1  may need to be reallocated to another server or may need to be removed to make room for a newer or better interface module. Host system  25  permits interface modules to be “hot swapped”, in other words replaced without shutting down the entire system. To this end, main power  27  can be withheld from interface module AP 1  at a process segment S 21 . Process segments S 12 , S 13 , S 15  and S 16  continue until host system  25  has determined (by accessing data from the power monitor) that the card has powered down correctly and that no current leakage exists from the external card that might present an unsafe condition for the user hot swapping the interface card. Once these conditions are met, standby power is also isolated from the card (effectively turning off the power monitoring capabilities of the interface card while data that has been stored in possible aforementioned storage locations remains intact) and the card may be safely removed.  
         [0014]     Normally, all external device and interconnecting cables are removed from interface card AP 1  prior to the withholding of main power  27  at method segment S 21 . Generally, if this is done, the power consumption associated with main power  27  should be zero once main power  27  is withheld. However, if external device  17  remains connected (e.g., due to a forgetful user), current leakage associated with a load represented by an external device  17  can result in continued power consumption. In this case, monitoring at method segment S 22  (a continuation of process segment S 12  beyond process segment S 12 ) and analysis at process segment S 23  (a continuation of process segment S 13  beyond method segment  21 ) can result in a detection of a leakage current. This detection can trigger a process segment S 24  in which a warning is issued. In a continuation of process segment S 15 , the manipulated data can be stored locally at process segment S 25 . In a continuation of process segment S 16 , the stored power data can be accessed by host computer software at step S 26 , which can also lead to a warning being issued.  
         [0015]     Whether a warning is issued as a result of process segment S 24  or process segment S 26 , removal of interface module AP 1  can be contraindicated. Instead, host computer  25  can be shut down, and interface module AP 1  removed or exchanged with all power off. This cold swap can prevent damage to the interface module AP 1 , external device  17 , and/or host computer  25  when interface module AP 1  is removed.  
         [0016]     The advantages of the invention are not limited to preventing problematic hot swaps. For example, process segment  14  can be used to warn when an interface module is operating beyond specifications, e.g., drawing more power than it is designed to handle. Also, the invention can be used to assist host computer  25  in determining precisely the amount of power used by all interface modules and other devices, e.g., memory modules, installed therein. Even if each module is operating within its specification, the total may exceed that permitted by the host system. Thus, tracking total power consumption can diagnose or forewarn of problems.  
         [0017]     While the invention is described in the context of a hot swap of an interface module for a server, it can also be applied to hot swaps of modular interfaces in different form factors and contexts. For example, it can be applied to PC Card (PMCIA Card) interfaces as well. In addition, the invention can be applied even where hot swapping is not provided for. For example, the invention can be used simply to monitor the condition of an interface module and to help determine a total power consumption for an incorporating system. These and other variations upon and modifications to the present invention are provided for by the present invention as defined by the following claims.