Instance Property


Opens a connection to a device that is not already open.


IOReturn (*openWithSessionRef)(void *self, IOFireWireSessionRef sessionRef);



SessionRef returned from getSessionRef call.


Pointer to IOFireWireAVCLibUnitInterface.

Return Value

Returns kIOReturnSuccess on success.


Sometimes it is desirable to open multiple user clients on a device. In the case of FireWire sometimes we wish to have both the FireWire User Client and the AVC User Client open at the same time. The technique to arbitrate this is as follows:

First open normally the device furthest from the root in the I/O Registry.

Second, get its sessionRef with the getSessionRef call.

Third, open the device further up the chain by calling this method and passing the sessionRef returned from the call in step 2.