What do you mean by port address? Do you mean the base address of the hardware? If so, you can use the Get_DAQ_Device_Info function to get the assigned base address of each device.
There are many example programs that are installed with LabWindows that I would suggest to look at. They are located within the ...\Program Files\National Instruments\MeasurementStudio\CVI\samples\daq directory. I hope this helps.
Regards,
Todd D.