ibbna() changes the GPIB interface board used to access the device specified by ud. Subsequent device level calls using the descriptor ud will assume the device is connected to the interface board specified by name. If you wish to specify a device's new access board by board index instead of name, you can use the IbcBNA option of ibconfig().
The name of a board can be specified in the configuration file gpib.conf.
On success, iberr is set to the board index of the device's old access board.
The value of ibsta is returned.