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Retrieving Device Relations

Last Updated: 7/30/2016

In Windows Vista and later versions of Windows, the unified device property model includes device relations properties. The unified device property model uses property keys to represent these properties.

Windows Server 2003, Windows XP, and Windows 2000 do not support the property keys of the unified property model, nor do they support the corresponding registry entry values that represent these properties. However, you can retrieve the corresponding information by calling Plug and Play (PnP) configuration manager functions. To maintain compatibility with earlier Windows versions, Windows Vista and later versions also support calling PnP configuration manager functions to retrieve device relations properties. However, you should use the property keys of the unified device property model to access the device relation properties.

For information about how to use property keys to access device driver properties, see Accessing Device Instance Properties (Windows Vista and Later).

For information about how to access the device relations properties on Windows Server 2003, Windows XP, and Windows 2000, see the following topics:

Retrieving Ejection Relations, Removal Relations, and Power Relations, and Bus Relations

Retrieving the Parent of a Device Instance

Retrieving the Children of a Device Instance

Retrieving the Siblings of a Device Instance

Retrieving Ejection Relations, Removal Relations, and Power Relations, and Bus Relations

To retrieve device relations information on Windows Server 2003, Windows XP, and Windows 2000, call CM_Get_Device_ID_List and supply the following parameter values:

  • Set pszFilter to a pointer to a NULL-terminated string that specifies the device instance identifier for which to retrieve relations information.

  • Set Buffer to a pointer to a buffer that receives a list of NULL-terminated device instance identifiers. The list is terminated by an additional NULL character. You can get the required buffer size by calling the CM_Get_Device_ID_List_Size function.

  • Set BufferLen to the size, in characters, of the Buffer buffer.

  • Set ulFlags to one of the following flags to retrieve the corresponding relations information:

    • CM_GETIDLIST_FILTER_EJECTIONRELATIONS

      The CM_GETIDLIST_FILTER_EJECTIONRELATIONS flag retrieves ejection relations, which is the same information that is provided by the DEVPKEY_Device_EjectionRelations device property in Windows Vista and later versions.

    • CM_GETIDLIST_FILTER_REMOVALRELATIONS

      The CM_GETIDLIST_FILTER_REMOVALRELATIONS flag retrieves removal relations, which is the same information that is provided by the DEVPKEY_Device_RemovalRelations device property in Windows Vista and later versions.

    • CM_GETIDLIST_FILTER_POWERRELATIONS

      The CM_GETIDLIST_FILTER_POWERRELATIONS flag retrieves power relations, which is the same information that is provided by the DEVPKEY_Device_PowerRelations device property in Windows Vista and later versions.

    • CM_GETIDLIST_FILTER_BUSRELATIONS

      The CM_GETIDLIST_FILTER_BUSRELATIONS flag retrieves bus relations, which is the same information that is provided by the DEVPKEY_Device_BusRelations device property in Windows Vista and later versions.

If the call to CM_Get_Device_ID_List succeeds, CM_Get_Device_ID_List retrieves the requested relations information and returns CR_SUCCESS. Otherwise, CM_Get_Device_ID_List returns one of the error codes with prefix "CR_" that are defined in Cfgmgr32.h.

Retrieving the Parent of a Device Instance

To retrieve the device instance identifier of a parent device on Windows Server 2003, Windows XP, and Windows 2000, follow these steps:

  1. Call the CM_Get_Parent function to retrieve a device instance handle to the parent device of a device instance.

  2. Call CM_Get_Device_ID to retrieve the device instance identifier that is associated with the device instance handle to the parent device that was retrieved by the previous call to CM_Get_Parent.

This information retrieved by using this procedure is the same as that represented by the DEVPKEY_Device_Parent property in the unified device property model of Windows Vista and later versions.

Retrieving the Children of a Device Instance

To retrieve the device instance identifiers of the child devices of a device instance on Windows Server 2003, Windows XP, and Windows 2000, follow these steps:

  1. Call the CM_Get_Child function to retrieve a device instance handle to the first child device that is associated with a device instance.

  2. Call CM_Get_Sibling as many times as it is necessary to enumerate all the sibling devices of the first child device that was retrieved by the call to CM_Get_Child.

  3. Call CM_Get_Device_ID to retrieve the device instance identifiers that are associated with the device instance handles that were returned by the calls to CM_Get_Child and CM_Get_Sibling.

This information retrieved by using this procedure is the same as that represented by the DEVPKEY_Device_Children property in the unified device property model of Windows Vista and later versions.

Retrieving the Siblings of a Device Instance

To retrieve the device instance identifiers of the sibling devices of device instance Abc on Windows Server 2003, Windows XP, and Windows 2000, follow these steps:

  1. Call the CM_Get_Parent function to retrieve a device instance handle to the parent device of device instance Abc.

  2. Call the CM_Get_Child function to retrieve a device instance handle to the first child device of the parent device of device instance Abc.

  3. Call CM_Get_Sibling as many times as is necessary to enumerate all the sibling devices of the first child device of the parent device. This enumeration will also return a handle to device instance Abc.

  4. Call CM_Get_Device_ID to retrieve the device instance identifiers that are associated with the device instance handles that were returned by the previous calls to CM_Get_Sibling. Remove the handle to device instance Abc from the list of sibling devices of the first child device of the parent device.

The information retrieved by using this procedure is the same as that represented by the DEVPKEY_Device_Siblings property in the unified device property model of Windows Vista and later versions. If a CM_*Xxx* function call listed in this section succeeds, the CM_*Xxx* function retrieves the requested information and returns CR_SUCCESS. Otherwise, the CM_*Xxx* function returns one of the error codes with prefix "CR_" that are defined in Cfgmgr32.h.

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